WaterSense
WaterSense® Notice of Intent to Develop a Draft
Specification for Spray Sprinkler Nozzles
WaterSense® Notice of Intent (NOI) to Develop a Draft Specification for
Spray Sprinkler Nozzles
I. Introduction
A spray sprinkler nozzle is a component of a sprinkler used for landscape irrigation. It is
provided in combination with a sprinkler body to distribute water to the landscape. In 2014, the
U.S. Environmental Protection Agency's (EPA's) WaterSense program released its Notice of
Intent (NOI) to Develop a Draft Specification for Landscape Irrigation Sprinklers, which
considered specification development for both spray sprinkler bodies and nozzles. However,
based on feedback received on the NOI indicating a lack of real-world water savings data and
concerns about nozzle performance criteria, EPA only moved forward with specification
development for spray sprinkler bodies. The WaterSense spray sprinkler body specification was
released in September 2017.1 WaterSense currently labels three irrigation products (weather-
based and soil moisture-based irrigation controllers and spray sprinkler bodies) that are more
water-efficient and perform as well as or better than standard models.
With this NOI, WaterSense is reconsidering specification development for spray sprinkler
nozzles. More recent water savings studies have indicated that certain types of spray sprinkler
nozzles can result in reduced water use, renewing WaterSense's interest in this product
category as a potential candidate for the WaterSense label. WaterSense estimates that these
more efficient spray sprinkler nozzles could use approximately 10 percent less water than
standard spray sprinkler nozzles. This is a conservative weighted average based on data from
the savings studies discussed in Appendix A. Assuming 10 percent savings, the average
household could save approximately 2,400 gallons of water annually by replacing standard
spray nozzles with high-efficiency spray sprinkler nozzles. On a national scale, WaterSense
estimates that nearly 26 million irrigation systems could be retrofitted with spray sprinkler
nozzles,2 which corresponds to an estimated 90 percent of irrigation systems.3 Offering a label
for spray sprinkler nozzles could be an effective way for WaterSense to further reduce water
use in residential irrigation systems.
Recent research has also identified notable stakeholder interest in a potential WaterSense label
for spray sprinkler nozzles, particularly among water utilities. Many water utilities offer rebate
programs for this product and are interested in more easily identifying spray sprinkler nozzle
models that save water compared to standard nozzles. Therefore, a WaterSense label would
1 EPA. 2017. WaterSense Specification for Spray Sprinkler Bodies, Version 1.0.
www.epa.gov/sites/default/files/2017-09/documents/ws-products-spec-ssb.pdf.
2 Schein, Letschert, Chan, Chen, Dunham, Fuchs, McNeil, Melody, Stratton, and Williams, 2017.
Methodology for the National Water Savings and Spreadsheet: Indoor Residential and
Commercial/Institutional Products, and Outdoor Residential Products. Lawrence Berkeley National
Laboratory. Schein etal. describes the detailed technical approach to WaterSense's stock accounting
practice for irrigation products using values available as of the publication date. As it is EPA's practice to
continuously update its work as data become available, the values referenced here are for the 2018
analysis, the most recent year available.
3 Dukes, Michael. 2021. Personal communication.
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WaterSense® Notice of Intent to Develop a Draft
Specification for Spray Sprinkler Nozzles
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allow more consistency across rebate programs and confidence that models selected for
rebates will result in water savings. Manufacturers have also expressed support for a
WaterSense label for this product category, since many currently market some models of spray
sprinkler nozzle as water-efficient and manufacture other WaterSense labeled irrigation
products.
There are no current federal requirements that regulate water use or performance of spray
sprinkler nozzles. However, as summarized in Section II Technical Background below,
WaterSense is aware of three industry standards that apply to this product category.
WaterSense is considering how these standards may inform potential water efficiency and
performance criteria.
This NOI to develop a draft specification for spray sprinkler nozzles is intended to share new
research on the efficiency and performance of these products, as well as the details of updated
water savings studies published since WaterSense's initial NOI from 2014. It also provides
consolidated information on the state of spray sprinkler nozzle technology. Wth this NOI,
WaterSense identifies preliminary criteria it is considering related to water efficiency and
performance. Finally, this NOI solicits feedback on key data gaps, which are identified
throughout the document. WaterSense requests that stakeholders share information that might
inform a decision about whether and how to develop a specification for this product category.
II. Technical Background
WaterSense has identified three industry standards that are relevant to this product category
and that will help inform the scope and water efficiency and performance criteria.
• The American Society of Agricultural Biological Engineers (ASABE)/lnternational Code
Council (ICC) 802-2020 Landscape Irrigation Sprinkler and Emitter Standard includes
requirements for spray sprinkler nozzles.
• ASAE/ASABE S398.1 Procedure for Sprinkler Testing and Performance Reporting
includes multiple test methods that could apply to a potential WaterSense specification.
• International Organization for Standardization (ISO) Standard 15886-2:2021 Agriculture
irrigation equipment - Sprinklers is another standard that could inform the test method
for a specification.
WaterSense primarily references definitions and test methods from ASABE/ICC 802-2020 in
this NOI. ASABE/ICC 802-2020 is the most widely accepted industry standard for this product
category and was the basis of the WaterSense Specification for Spray Sprinkler Bodies.
ASABE/ICC 802-2020 references ASAE/ASABE S398.1.
According to ASABE/ICC 802-2020, a sprinkler is defined as:4
• Sprinkler: An emission device consisting of a sprinkler body with one or more orifices to
convert irrigation water pressure to high-velocity water discharge through the air,
discharging a minimum of 0.5 gallons per minute (gpm) at the largest area of coverage
4 ICC. 2020. ASABE/ICC 802-2020 Landscape Irrigation Sprinkler and Emitter Standard.
https://codes.iccsafe.orq/content/ICC8022020P1/chapter-2-definitions.
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Specification for Spray Sprinkler Nozzles
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available for the nozzle series when operated at 30 pounds per square inch (psi) or more
with a full-circle pattern.
In other words, a "sprinkler" is the combination of a sprinkler body and nozzle, as shown in
Figure 1. As discussed below, there are different types of sprinkler bodies.
Figure 1. A diagram showing a spray sprinkler, consisting of a sprinkler body and a
nozzle. (Image courtesy of Irrigation Association, Smart Water Application Technologies)
ASABE/ICC 802-2020 defines the two components as follows:5
• Sprinkler body: The exterior case or shell of a sprinkler incorporating a means of
connection to the piping system, designed to convey water to a nozzle or orifice.
• Nozzle: The discharge opening of a sprinkler used to control the volume of discharge,
distribution pattern and droplet size.
ASABE/ICC 802-2020 further defines three types of sprinkler bodies (described here for
context):6
• Spray sprinkler body: A sprinkler body that does not contain components to drive the
rotation of the nozzle or orifice during operation and lacks an integral control valve.
• Rotor sprinkler body: A sprinkler body that contains components to drive the rotation of
the nozzle or orifice during operation and lacks an integral control valve.
• Valve-in-head sprinkler body: A sprinkler body that contains an integral control valve.7
Of these, spray sprinkler bodies are currently eligible for the WaterSense label in accordance
with the WaterSense Specification for Spray Sprinkler Bodies.
5 Ibid.
6 Another category is impact sprinklers, which are not mentioned in ASABE/ICC 802-2020. They are a
small part of the industry but are still commercially available.
7 ICC. 2020. Op. cit.
w
Nozzle
Sprinkler body
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WaterSense® Notice of Intent to Develop a Draft
Specification for Spray Sprinkler Nozzles
There is no explicit definition for spray sprinkler nozzles within ASABE/ICC 802-2020, so for the
purpose of this NOI, WaterSense developed the following definition based on related definitions
included in the standard:
• Spray sprinkler nozzle: The discharge opening of a spray sprinkler used to control the
volume of discharge, distribution pattern, and droplet size. These nozzles are attached
to spray sprinkler bodies that do not contain components to drive the rotation of the
nozzle during operation and lack an internal control valve.
Though the general product category of spray sprinkler nozzles is not defined, the ASABE/ICC
802-2020 standard defines one specific type of spray sprinkler nozzle:
• Multi-stream, multi-trajectory (MSMT) nozzles: Nozzles designed to distribute
discharge water in a number of individual streams, of varying trajectories, which rotate
across the distribution area.8
MSMT sprinkler nozzles are only available as rotating models. The rotation is driven by the
nozzle, not the spray sprinkler body.9
Figure 2 and Figure 3 illustrate the difference in spray patterns from standard (i.e., non-MSMT)
and MSMT spray sprinkler nozzles, respectively. The distinct spray pattern of MSMT nozzles is
the most apparent difference between the two types of nozzles.
Figure 2. Examples of fan spray pattern from standard sprinkler nozzles (Photos
courtesy of Hunter® Industries Incorporated.)10
8 Ibid.
9 Baum-Haley, Melissa. 2014. Evaluation of Potential Best Management Practices-Rotating Nozzles. The
California Urban Water Conservation Council. Sacramento, CA.
10 Hunter Industries, Incorporated. 2021. Photo Library. Accessed 05 November 2021.
https://www.hunterindustries.com/en-metric/photos.
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Specification for Spray Sprinkler Nozzles
Figure 3. Example of multi-stream pattern from MSMT sprinkler nozzles {Photos courtesy
of Hunter Industries Incorporated.)11
Most commonly, spray sprinkler nozzles and bodies are sold separately, though in retail
settings, the two products can be sold together. MSMT nozzles are typically compatible with
spray sprinkler bodies manufactured by a different brand.
WaterSense would like stakeholder input on its product category definition of "spray
sprinkler nozzle."
III. Scope
WaterSense intends to define the scope of a potential specification to include nozzles intended
for use in spray sprinklers. Therefore, the product category only applies to sprinkler nozzles that
connect to spray sprinkler bodies, which do not have components that drive rotation.12 Figure 4
shows the relationship among spray sprinkler nozzles, other components of a spray sprinkler,
and other types of sprinklers.
11 Ibid.
12 Based on the definitions included in ASABE/ICC 802-2020.
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AA/atCl*ScUSC Specification for Spray Sprinkler Nozzles
Figure 4. Flow chart illustrating the types of irrigation sprinklers and their components.13
Gear-driven rotor sprinkler bodies ("rotor sprinklers" in Figure 4) have components that drive the
rotation of the nozzle or orifice during operation; spray sprinkler bodies do not have these
components. WaterSense is not aware of any versions of MSMT nozzles for rotor sprinklers.
Valve-in-head sprinklers have an integral control valve intended to be operated from a remote
location. Rotor and valve-in-head sprinklers are physically different products from spray
sprinklers, and the standards and savings studies discussed in this NOI do not apply to them.
WaterSense does not intend for this product category to include sprinkler nozzles that are used
exclusively in agricultural irrigation systems, which are fundamentally different products with
different testing requirements. WaterSense also intends to exclude other irrigation emission
devices, such as bubblers, hose-end water products, and microirrigation emission devices (i.e.,
those that discharge water in the form of drops or continuous flow rates at less than 30 gallons
of water per hour when operated at 30 psi) from a specification.14 The exclusion of
microirrigation devices effectively excludes drip emitters, drip line emitters, and point-source
13 Note that a "sprinkler" is defined as the combination of sprinkler body and nozzle. Spray sprinkler
nozzles are the intended scope for a specification, as shown above.
14 ICC. 2020. Op. cit.
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Specification for Spray Sprinkler Nozzles
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emitters, as well as micro sprays. These products have a different structure, purpose, and test
method compared to spray sprinkler nozzles.
WaterSense would like stakeholder feedback on the intended scope of the specification.
IV. Water Efficiency and Performance
As described in Section VII Estimated Water Savings, WaterSense has estimated that some
types of spray sprinkler nozzles use approximately 10 percent less water than standard spray
sprinkler nozzles. WaterSense has found that spray sprinkler nozzles marketed as "high-
efficiency" are MSMT nozzles that emit multiple streams of water at multiple trajectories. Based
on WaterSense's research, water utilities with rebate programs for spray sprinkler nozzles often
require MSMT nozzles. Furthermore, although the authors used a variety of terms for the
product, MSMT nozzles were considered a more water-efficient option in the water savings
studies documented in Appendix A.
It is possible that manufacturers could develop other types of high-efficiency spray sprinkler
nozzles in the future. To be inclusive of future developments in the market, WaterSense uses
the phrase "high-efficiency spray (HES) sprinkler nozzle" (which includes MSMT nozzles) in this
NOI to differentiate the products that WaterSense is considering labeling.
Based on its research, WaterSense identified four attributes that appear to be different between
HES and standard spray sprinkler nozzles. These attributes are:
• Application rate,
• Distribution uniformity,
• Distance of throw, and
• Droplet size and spray pattern.
This section describes each attribute and evaluates whether it could be used as either a water
efficiency or performance criterion in a WaterSense specification to help differentiate HES
models. Some of these attributes have test methods and associated data. If so, WaterSense
reviewed the requirements in the available standards and identified material that is relevant to
the water efficiency and performance of spray sprinkler nozzles. This section discusses
available test methods15 and associated performance data for each attribute, if available, and
considers whether any additional requirements for these products should be included in a
specification.
At the end of this section, Table 1 provides details on attributes of MSMT sprinkler nozzles for a
variety of product models. Table 2 provides a summary of these attributes based on a review of
manufacturer literature for products currently on the market.
15 Although WaterSense references test methods from ASABE/ICC 802-2020 throughout Section IV
Water Efficiency and Performance, WaterSense has not determined whether the test methods have been
validated.
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Specification for Spray Sprinkler Nozzles
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Application Rate
The application rate, also known as precipitation rate, is the rate at which a sprinkler applies
water to a given area. As explained in ASABE/ICC 802-2020, application rate relates to the flow
rate and total irrigated area, as follows:
Equation 1.16
• 96.25 is a constant used to convert gallons per minute (gpm) over an area in square feet
to inches per hour;
• Flow rate is the cumulative flow rate from all sprinklers in the area, as measured in gpm;
• Total area is the irrigated area in square feet.
Application rate is typically expressed in inches per hour. It is directly correlated with the flow
rate from the sprinkler and indirectly correlated with irrigated area. Sprinkler nozzles with higher
application rates apply more water to an area in the landscape in a given amount of time. HES
sprinkler nozzles generally have lower application rates than standard sprinkler nozzles. As
shown in Table 2, most MSMT sprinkler nozzles have application rates equal to or less than 1.0
inch per hour, whereas standard sprinkler nozzles have application rates greater than 1.0 inch
per hour. Nozzles with lower application rates are considered more efficient, as they allow more
water to percolate into the soil rather than flow offsite as runoff.17
Sprinkler nozzles can be designed to apply water at the same application rate at all arcs
(degrees of coverage) and radii (distance of throw), meaning that the application rate will be
equivalent across the irrigated area. This feature is known as "matched precipitation." In uniform
landscapes such as turfgrass, matched precipitation nozzles help ensure that all areas of the
landscape receive approximately the same amount of water during an irrigation event.
Manufacturers advertise application rate (typically listed as "precipitation rate") and the
availability of matched precipitation for spray sprinkler nozzles. As shown in Table 2, most
MSMT sprinkler nozzles and some standard spray sprinkler nozzles offer matched precipitation.
Pressure regulation can also can directly and independently affect application rate. Pressure
regulating spray sprinkler bodies create a constant flow rate to the sprinkler nozzle regardless of
supply pressure. Without pressure regulation, spray sprinkler bodies may apply water at higher
rates than the sprinkler nozzle's specified application rate.
16 Kitsap Public Utility District. 2018. Determine Your Sprinkler System's Precipitation Rate. Accessed 14
February 2022. www.kpud.org/sprinklerRates.php.
17 Baum-Haley. 2014. Op. cit.
Application rate (inches per hour) =
96.25 x flow rate (gpm)
total area (ft2)
Where:
and
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Specification for Spray Sprinkler Nozzles
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Spray sprinkler nozzles are not necessarily pressure-regulating by design. However, as
described in Section V Existing Performance Data, preliminary research results suggest that
HES sprinkler nozzles provide a similar effect as pressure regulation, though likely not to the
same extent as pressure-regulating sprinkler bodies.
Test Methods and Associated Data
There are two published evaluation methods for application rate. ASABE/ICC 802-2020
provides a method to calculate the theoretical (i.e., gross) application rate as a function of
pressure by dividing the average flow rate at a given pressure by the average pattern collection
area for a given pressure.18 The Irrigation Association's Smart Water Application Technologies
(SWAT) program published a draft protocol for spray sprinkler nozzles in 2014. The draft
protocol calculates gross precipitation rate by dividing flow rate by irrigated area and calculates
net precipitation rate based on water measured in catchment devices.19
WaterSense is not aware of a test method for evaluating matched precipitation or pressure
regulation provided by spray sprinkler nozzles.
As discussed in Section V Existing Performance Data, Dr. Michael Dukes of the University of
Florida conducted research to evaluate whether spray sprinkler nozzles could be differentiated
based on flow rate. Dr. Dukes developed a test method that aligns with ASABE/ICC 802-2020.
His results indicate that flow rate is substantially lower in HES sprinkler nozzles compared to
their standard counterparts. Based on these findings, ASABE/ICC 802-2020 could be used to
differentiate spray sprinkler nozzles. The application rate can be calculated from flow rate by
measuring irrigated area and using Equation 3-1 in ASABE/ICC 802-2020, which aligns with
Equation 1 above.
Application Rate as Water Efficiency or Performance Criteria
WaterSense is considering using application rate as a water efficiency criterion to identify HES
sprinkler nozzles. For a spray sprinkler nozzle to earn the WaterSense label, WaterSense would
propose two thresholds for application rates: one at the manufacturer's recommended operating
pressure and one at high pressure. WaterSense would set the thresholds based on Dr. Dukes'
data and reference the test method in ASABE/ICC 802-2020.
For the purposes of this NOI, WaterSense is proposing that each radius in a model's product
family be tested (for example, 12- and 15-feet radii versions of a model) at the full circle pattern
only. If the nozzle has an adjustable radius, WaterSense is considering requiring it to be tested
at the maximum radius.
WaterSense is seeking stakeholder feedback on its proposal to use application rate (at
recommended operating pressure and high pressure) as a water efficiency criterion for
spray sprinkler nozzles. WaterSense is also interested in whether any manufacturers
18 ICC. 2020. Op tit.
19IA. October 2014. Spray Head Sprinkler Nozzles Performance Characteristics: Equipment Functionality
Testing Protocol, Version 3.1. www.irriqation.org/SWAT/About/Testinq-
Protocols/Archives/SWAT/About/Archives.aspx?hkev=a46d9517-4345-4e01-89cb-
5e0135da535e#SpravHeadSprinklerNozzles.
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currently use the ASABE/ICC 802-2020 test method for application rate and, if so, would
be willing to share masked data with WaterSense.
Additionally, WaterSense requests stakeholder opinions on using the following
parameters to evaluate spray sprinkler nozzles:
• Test each radius in a model's product family at the full circle pattern only; and
• Test models with an adjustable radius at the maximum radius.
Although spray sprinkler nozzles are not necessarily pressure-regulating by design, Dr. Dukes'
results provide some evidence that MSMT nozzles may provide a similar effect as pressure
regulation. (See Section V Existing Performance Data for more details.) As a result,
WaterSense would not need to include a separate test method for pressure regulation but would
incorporate it into the evaluation of application rate.
To evaluate matched precipitation, WaterSense is proposing that licensed certifying bodies
evaluate application rates across an entire family of models. WaterSense is not aware of an
industry standard variance in application rates that constitutes matched precipitation for spray
sprinkler nozzles. WaterSense would need to identify an acceptable variance for the purposes
of the specification.
WaterSense seeks input on whether it should require spray sprinkler nozzles to have
matched precipitation to be eligible for the WaterSense label. What would be an
acceptable variance in application rates to ensure matched precipitation? If WaterSense
requires matched precipitation, how should EPA verify the data?
Distance of Throw
Distance of throw refers to the distance to which the sprinkler nozzle disperses water onto the
surrounding landscape. It is typically presented as a radius. Distance of throw can be used to
calculate total irrigated area, which is used to calculate application rate (see Equation 1).
The distance of throw is used to determine the appropriate spacing between sprinklers. It
primarily relates to water efficiency because of its influence on irrigation system design in a new
landscape.
HES sprinkler nozzles tend to have larger distances of throw than standard sprinkler nozzles (as
shown in Table 2). It is possible that a longer distance of throw would allow irrigation contractors
to increase the size of an irrigation zone and use fewer sprinklers compared to a system with
standard spray nozzles, thus reducing the number of sprinklers in a new system. The landscape
should use less water overall, because the cumulative application rate from all sprinklers is
lower. Using fewer sprinklers could also substantially decrease the cost of a new irrigation
system. A study by John Wascher estimated that contractors could save up to 45 percent on
their bids for materials alone (e.g., sprinklers, valves, piping) when designing a landscape for
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Specification for Spray Sprinkler Nozzles
MSMT nozzles as compared to standard sprinkler nozzles.20 Figure 5, adapted from Wascher's
report, illustrates the difference between irrigation system layouts for standard and MSMT
sprinkler nozzles. The diagram shows layouts with 55 standard sprinkler nozzles (left) and 34
MSMT nozzles (right).
Figure 5. Comparison of irrigation layout with standard sprinkler nozzles (left) and MSMT
sprinkler nozzles (right). Figure adapted from a 2011 publication by John Wascher.21
When standard sprinkler nozzles are replaced by HES sprinkler nozzles in an existing
landscape (i.e., a retrofit), the number of sprinklers typically remains consistent because
contractors are unlikely to redesign the irrigation system. As a result, any water savings in the
landscape will not be attributable to fewer sprinklers and, indirectly, distance of throw. Instead,
contractors will simply replace standard sprinkler nozzles with HES sprinkler nozzles, then
adjust them to ensure head-to-head coverage. In some instances, irrigation contractors may cap
sprinkler bodies if it is determined they are no longer needed.
WaterSense is interested in feedback from irrigation contractors about whether they are
likely to incorporate HES sprinkler nozzles in bids for new irrigation systems, any factors
that might influence their decision (i.e., new installation vs. retrofit), and whether HES
sprinklers reduce the cost of materials in practice.
20 Wascher, John. 2011. Multi-Stream, Multi-Trajectory Nozzles; How They Save Water, Labor and
Installation Costs. Irrigation Association Technical Papers.
www, irrigation. orq/IA/FiieUploads/IA/Resources/TechnicalPapers/2011 /Multi-StreamMuiti-
TraiectorvNozziesCMSM'DAndHowThevSaveWaterLaborAndlnstallationCosts.pdf.
21 Images from Wascher, John. Op. cit.
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Test Methods and Associated Data
ASABE/ICC 802-2020 includes a test method to calculate distance of throw. Testing is
conducted at the minimum, recommended, and maximum operating pressures, as indicated by
the manufacturer. Sprinkler nozzles are tested with a specified type of grid depending on their
spray pattern (i.e., regular and symmetrical, or circular).22 ASABE/ICC 802-2020 references
ASAE/ASABE S398.1.23
WaterSense is not aware of any distance of throw data generated from the test methods in
standards or other research studies. However, manufacturers typically advertise distance of
throw for different nozzle models. They may be using ASAE/ASABE S398.1 to measure
distance of throw. WaterSense intends to engage with certifying bodies and manufacturers to
determine whether the advertised distance of throw is based on data generated as part of
testing in accordance with ASAE/ASABE S398.1.
Distance of Throw as Water Efficiency or Performance Criteria
WaterSense is considering requiring distance of throw as part of its water efficiency criterion,
since it is used to calculate application rate in ASABE/ICC 802-2020. Measuring distance of
throw would also help ensure product performance.
WaterSense is considering requiring that the measured distance of throw be at least equal to,
and no more than a specified percent above, the manufacturer's rated distance of throw. These
thresholds would ensure that a manufacturer's rated value for distance of throw is accurate (i.e.,
that the published distance of throw is met without excessive overspray).
WaterSense seeks stakeholder feedback on whether ASAE/ASABE S398.1 is an
appropriate test method for distance of throw.
Do stakeholders believe it is reasonable for WaterSense to require the tested distance of
throw to align with the value reported by the manufacturer? WaterSense is also
interested in stakeholder input on the appropriate percent exceedance (e.g., percentage
greater than the rated distance of throw) to prevent water waste due to overspray.
Distribution Uniformity
Distribution uniformity (DU) is a measure of how evenly water is applied to a landscaped area.
DU can be considered at the scale of the landscape (i.e., water applied by all sprinkler nozzles)
or the sprinkler nozzle (i.e., water applied to the irrigated area of the individual sprinkler). In
theory, landscapes with lower DU are expected to use more water, as the irrigation system
would be programmed to water to the driest part of the landscape, resulting in overwatering in
other areas. Standard sprinkler nozzles are more likely to irrigate unevenly compared to MSMT
sprinkler nozzles, based on data from field studies. DU may also be influenced by the uniformity
of individual sprinkler nozzles (e.g., if each stream is emitted at a different angle, it will not
interfere with adjacent streams24); wind conditions; and the design, installation, and
22 ICC. 2020. Op. tit.
23 ASABE. 1985. ASAE/ASABE S398.1 Procedure for Sprinkler Testing and Performance Reporting.
https://elibrarv.asabe.orq/abstract.asp?aid=41295&t=3&dabs=Y&redir=&redirType=.
24 Wascher, John. Op. tit.
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maintenance of the irrigation system. As shown in Table 2, researchers have measured DUs in
the range of 34 to 78 percent for standard spray sprinkler nozzles and 58 to 81 percent for
MSMT sprinkler nozzles.
Despite expectations, field studies have not demonstrated that higher system DU results in
increased water savings. See Application as Water Efficiency or Performance Criteria below for
more information.
Test Methods and Associated Data
ASABE/ICC 802-2020 includes a uniformity test for spray sprinkler nozzles conducted on
individual nozzles. Uniformity is modeled using data collected during the distance of throw test.
The standard indicates that the modeled uniformity will generate a value equivalent to the lower
quarter DU (DUlq) (Equation 2). DUlq is a "ratio of the average of the lowest one-fourth of
measurements of irrigation water to the average of all measurements captured by collection
devices."25 A certification body models DUlq using the lowest and highest application rates as
bounds.
Equation 2.26
• Vlq is the volume of the average of lowest quarter of samples from the array of collectors
used as part of the test method for determination of application rate, and
• Vavg is the average recorded volume as acquired from collectors in consistent units.
WaterSense is not aware of any compiled dataset related to DU that has been generated in
accordance with the ASABE/ICC 802-2020 test method. Some manufacturers advertise DU for
different nozzle models, but WaterSense is not aware of the test method used to calculate it.
Distribution Uniformity as Water Efficiency or Performance Criteria
Early studies on water savings associated with MSMT sprinkler nozzles focused on DU as the
likely mechanism for anticipated water savings. Researchers and utilities suggested that MSMT
sprinkler nozzles might use less water and result in healthier landscapes because they
distribute water more evenly. Since DU quantifies this metric, stakeholders suggested that DU
might be an appropriate way to measure water efficiency, and some researchers attempted to
quantify the range of DU that would result in water savings. Many of these studies included
25 ICC. 2020. Op. cit
26 Ibid.
Where:
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irrigation audits conducted in a controlled environment, such as a field or concrete surface.27 28'
29,30,31,32 while many of these studies reported higher DUs for MSMT sprinkler nozzles, the
researchers did not observe the expected water savings.
At this point, WaterSense only has DU data from field studies reported in the literature.
However, a potential specification would require licensed certifying bodies to use a laboratory-
based test method to measure DU. Consequently, WaterSense would need to review DU data
generated in accordance with laboratory testing to develop a threshold for DU in a potential
specification. It is possible that WaterSense could obtain this data from manufacturers, who can
calculate DU based on data generated from the laboratory-based test method for distance of
throw.
WaterSense invites manufacturers to submit laboratory data on DU for HES and standard
spray sprinkler nozzles. WaterSense also invites manufacturers to indicate whether they
collect DU data in accordance with ASABE/ICC 802-2020 or through another method.
Based on laboratory data, WaterSense could take two approaches to establishing a threshold
for DU. WaterSense could identify a threshold that indicates a minimum level of performance.
Alternatively, WaterSense could identify a DU value that differentiates between HES and
standard spray sprinkler nozzles, with the value of the former expected to be higher than the
latter. In either case, WaterSense would likely require DU to be calculated based on the
ASABE/ICC 802-2020 distance of throw test conducted to measure application rate for
WaterSense certification.
27 Dukes, Michael D., Haley, Melissa, B., and Stephen A. Hanks. 2006. Sprinkler Irrigation and Soil
Moisture Uniformity. Proceedings of the 27th Annual International Irrigation Show, San Antonio, TX.,
November 5-7, 2006.
www.irriqation.orq/IA/FileUploads/IA/Resources/TechnicalPapers/2006/SprinklerlrriqationAndSoilMoisture
Uniformitv.pdf.
28 Kieffer, Douglas L. and Mike Huck. 2008. A Comparison of Fairway Distribution Uniformity Computed
with Catch Can Data and with Soil Moisture Data from Three Sampling Depths. Paper presented at the
29th Annual Irrigation Show. Anaheim, CA. November 2-4, 2008.
www.specmeters.com/assets/1/7/Kieffer-Huck Abstract2197.pdf.
29 Vis, E, Kumar, R., and S. Mitra. 2007. Comparison of Distribution Uniformity of Soil Moisture and
Sprinkler Irrigation in Turfgrass. Project funded by the California Landscape Contractors Association
Environmental Research Funding Program.
30 Mecham, Brent Q. 2002. Comparison of Catch Can Distribution Uniformity to Soil Moisture Distribution
Uniformity in Turfgrass and the Impacts of Irrigation Scheduling. Northern Colorado Water Conservancy
District. Loveland, CO.
www.irriqation.orq/IA/FileUploads/IA/Resources/TechnicalPapers/20Q2/ComparisonOfCatchCanDistributi
onUniformitvToSoilMoistureDistributionUniformitvlnTurfqrassAndThelmpactsOnlrriqationSchedulinq.pdf.
31 Kieffer, Douglas L. and T. Sean O'Conner. 2007. Managing Soil Moisture on Golf Greens Using a
Portable Wave Reflectometer. Paper presented at the 28th Annual Irrigation Show. San Diego, CA.
December 9-11, 2007. www.specmeters.com/assets/1/7/kieffer-OConnor TDR300.pdf.
32 Sovocool, K., Morgan, M., and M. Drinkwine. 2009. Field Study of Uniformity Improvements from Multi-
Stream Rotational Spray Heads and Associated Products. Irrigation Association Technical Library.
https://www.irriqation.orq/IA/FileUploads/IA/Resources/TechnicalPapers/2009/FieldStudvQfUniformitvlmp
rovementsFromMulti-StreamRotationalSpravHeadsAndAssociatedProducts-PreliminarvResults.pdf.
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Specification for Spray Sprinkler Nozzles
WaterSense
WaterSense would like stakeholder input on whether DU should be used in a
specification to establish a minimum level of performance or used to differentiate HES
and standard spray sprinkler nozzles.
Finally, as discussed above, WaterSense is not aware of any studies or data connecting DU to
water savings.
WaterSense invites stakeholders to submit data pertaining to the relationship between
DU and water savings and/or performance (e.g., landscape health).
Droplet Size and Spray Pattern
As noted in Table 2, standard sprinkler nozzles produce fine droplets (resembling mist) that can
be blown by the wind and diverted from their intended destination. MSMT sprinkler nozzles have
a spray pattern that creates larger droplets and reduces misting.33 The spray pattern allows
MSMT sprinkler nozzles to distribute water more evenly across the landscape despite their
lower flow rate. The larger droplet size could also prevent water from being applied to
undesirable areas, such as hardscapes, potentially decreasing the total water applied for
irrigation.
Test Methods and Associated Data
ISO Standard 15886-2:2021 Agriculture irrigation equipment - Sprinklers includes a drop size
test in Annex A to Part 2. The stated purpose of the test is to "characterize the distribution of
drop sizes discharged by the water jet of a sprinkler." For this test, measurements are collected
in multiple concentric rings within the sprinkler nozzle's radius of throw at different pressures.
These measurements are used to calculate the number of drops collected in groupings of
diameter sizes.34
WaterSense is not aware of any data on drop size or spray pattern collected in accordance with
ISO Standard 15886-2:2021 or published in any research study.
Droplet size or spray pattern as Water Efficiency or Performance Criteria
To date, WaterSense is not aware of any published research measuring droplet size or data
demonstrating a correlation between droplet size and water savings. One study suggested that
larger droplet size could result in greater resistance to wind.35 It is possible that droplet size
could influence irrigation schedules, especially in windy regions. Landscapes with standard
spray sprinkler nozzles may have brown spots if the wind disperses the irrigation water. The
irrigation scheduler may respond by increasing irrigation runtimes to address the brown spots.
In contrast, MSMT sprinkler nozzles produce larger droplets that may be more resistant to wind,
meaning that more of the water emitted is likely to travel to and be used by the plants for which
it was intended, reducing the likelihood of brown spots.
33 Dukes, Michael. 2021. Personal communication.
34 International Organization for Standardization (ISO). 2021. ISO 15886-2: 2021 Agriculture irrigation
equipment - Sprinklers, www.iso.org/standard/77748.html.
35 Baum-Haley, Melissa. 2014. Op. cit.
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Specification for Spray Sprinkler Nozzles
It may be possible to connect droplet size or spray pattern to performance, but WaterSense is
not aware of any related data.
WaterSense invites stakeholders to share data on droplet size and water efficiency,
especially collected in accordance with ISO Standard 15886-2:2021. WaterSense
welcomes feedback on whether stakeholders think droplet size should be included as a
criterion in a WaterSense specification.
Summary and Comparison of Nozzle Features
Table 1 lists the technical features of common MSMT nozzles currently on the market. As
described earlier, MSMT nozzles are generally considered to be HES sprinkler nozzles.
Table 1. Product Details for Common MSMT Sprinkler Nozzles Used in Residential
Landscapes
Brand
Model Name
Application
Rate (inches
per hour) for
a Range of
Radii
Matched
Precipitation
Radius
(feet)
Rotating?3
Multi-
stream?
Recommended
Operating
Pressure (psi)
Hunter®
MP Rotator®
0.37 to 0.45
Yes
8 to 35
Yes
Yes
40
Hunter
MP Rotator
MP800
0.79 to 0.84
Yes
6 to 16
Yes
Yes
40
Rain
Bird®
R-VAN
Rotary
Nozzles
0.61 to 0.64
Yes
8 to 24
Yes
Yes
45
Rain Bird
RN High
Efficiency
Rotary
Nozzles
0.61 to 0.65
Yes
13 to 24
Yes
Yes
45
Toro®
Precision™
Series Spray
Nozzlesb
1.0 to 1.1
Yes
5 to 15
Noc
Yes
30
Toro
Precision™
Series
Rotating
Nozzles
0.55 to 0.67d
Yes
14 to 26
Yes
Yes
45
K-Rain®
Rotary
Nozzles
0.42 to 0.49e
Yes
13 to 30
Yes
Yes
Not specified.
Can operate at
30-50 psi.
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Table 1. Product Details for Common MSMT Sprinkler Nozzles Used in Residential
Landscapes
Brand
Model Name
Application
Rate (inches
per hour) for
a Range of
Radii
Matched
Precipitation
Radius
(feet)
Rotating?3
Multi-
stream?
Recommended
Operating
Pressure (psi)
K-Rain
Fully
Adjustable
Rotary
Nozzles
0.42 to 0.51e
Yes
13 to 28
Yes
Yes
Not specified.
Can operate at
30-50 psi.
a This references a spray sprinkler nozzle that rotates.
b Toro Precision Series Spray Nozzles are available in pressure-compensating and non-pressure-
compensating models. This table presents data for non-pressure-compensating models.
c This sprinkler nozzle creates an oscillating flow, rather than a rotating flow. According to Toro, there is a
device inside the nozzle that "creates one or more high-frequency oscillating streams." In person, the
Precision Series Spray Nozzles appear to have a more stream-like pattern than a standard sprinkler
nozzle.
d Toro does not report application rates at the recommended operating pressure of 45 psi for the
Precision Series Rotating Nozzles. This table shows application rates at 40 psi.
e K-Rain does not specify a recommended operating pressure for this nozzle. The table shows application
rates at 40 psi.
Table 2 compares the attributes discussed in Section IV Water Efficiency and Performance. It
compares the ranges of the attribute for MSMT and standard spray nozzles and includes
potential effects on water use. Again, the term "MSMT sprinkler nozzle" is used to reflect the
products currently available on the market.
Table 2. Sprinkler Nozzle Features and Potential Effect on Water Use
Feature of
Nozzles
MSMT Sprinkler
Nozzles
Standard
Sprinkler Nozzles
Factors Affecting
Water Use
Expected Effect on
Water Use
Application
rate
0.39 to 1.1 inches per
hour3
1.25 to 4.81
inches per hour3
Irrigation schedule
runs longer for
lower precipitation
rate
Potential decrease in
water use, dependent
on length of runtimes.
Matched
precipitation
All identified MSMT
products have
matched
precipitation13
Available for some
standard sprinkler
nozzlesb
N/A
Potential decrease in
water use
Distance of
throw (radii)
5 to 30 feetb
4 to 18 feetb
May influence
irrigation design in
new systems
May decrease, but no
known research
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EPA
Water Sense
WaterSense® Notice of Intent to Develop a Draft
Specification for Spray Sprinkler Nozzles
Table 2. Sprinkler Nozzle Features and Potential Effect on Water Use
Feature of
Nozzles
MSMT Sprinkler
Nozzles
Standard
Sprinkler Nozzles
Factors Affecting
Water Use
Expected Effect on
Water Use
DU
58 to 81 percent;
weighted average of
69 percent0
34 to 78 percent;
weighted average
of 47 percent0
Irrigation system
design and
sprinkler
placement
None demonstrated
in field studies
Droplet size
Larger droplets at
high pressure
Smaller
droplets/mist at
high pressure
May result in less
wind drift potential,
but no known
research
May decrease, but no
known research
a Minimum and maximum application rates were selected for square spacing at full coverage and
manufacturer's recommended pressure across all brands, based on a review of sprinkler nozzles
manufactured by Hunter, Rain Bird, Toro, and K-Rain. Radii may differ.
b Based on review of sprinkler nozzles manufactured by Hunter, Rain Bird, Toro, and K-Rain.
c As identified from literature review of Kumar and Vis 2009; Hattendorf & Crookston 2011; Wascher
2011; Solomon eta!., 2007; and Sovocool eta!., 2009.
Possible Additional Criteria From Existing Standards
The WaterSense Specification for Spray Sprinkler Bodies includes additional criteria from
ASABE/ICC 802-2020 that help ensure WaterSense labeled products are of high quality, in
addition to being high performing.36 WaterSense could consider including similar requirements
in a specification for HES sprinkler nozzles. WaterSense is considering incorporating the
following sections in ASABE/ICC 802-2020 by reference. These sections establish requirements
for sprinkler design and product marking.
302.1. Rated temperature
302.2. Inlet connections
302.4. Servicing
302.5. Adjustments
302.6. Burst pressure
304.1.1. Units
304.1.2. Location
304.1.3 Manufacturer name
304.1.4. Connectors
304.1.5. Nozzle series marking
304.1.6. Instructions
304.2. Marking of sprays and rotors (as applicable)
36 ICC. 2020. Op. cit.
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WaterSense welcomes stakeholder feedback on whether to require these sections of
ASABE/ICC 802-2020 in a potential specification.
V. Existing Performance Data
As discussed previously, Dr. Dukes is conducting research on the water efficiency of spray
sprinkler nozzles, which will help inform criteria if WaterSense decides to move forward with a
specification. Dr. Dukes developed a test method based on ASABE/ICC 802-2020 to measure
the flow rate of standard and HES sprinkler nozzles through a non-pressure-regulating sprinkler
body, as well as variations in flow rate across a range of water pressures. As explained in
Section IV Water Efficiency and Performance, flow rate can be converted to application rate
using the methodology in ASABE/ICC 802-2020.
Dr. Dukes is currently analyzing additional data. WaterSense will incorporate his data if the
program proceeds with a draft specification.
Figure 6 shows preliminary results from Dr. Dukes' research for a single test comparing flow
rate for HES and standard sprinkler nozzles across a range of pressures.37
7.0
E
Q.
B
ru
i—
I
1.0
0.0
30 45 60 75 S5 75 60 45 30
Pressure (psi)
non-HES HES
3.0
Figure 6. Preliminary results from a 15-foot full-circle single test comparison conducted
as part of Dr. Michael Dukes' research on HES sprinkler nozzles and standard sprinkler
nozzles (abbreviated as "non-HES").
As shown in Figure 6, the HES sprinkler nozzle had a 44 percent lower flow rate than the
standard sprinkler nozzle at the recommended operating pressures (45 and 30 psi,
respectively). The flow rate for HES sprinkler nozzles was consistent across the range of
pressures, similar to the effect of pressure regulation. For example:
37 Dukes, Michael. 2021. Personal communication.
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WaterSense
• The maximum tested pressure (85 psi) represents conditions without pressure
regulation in the sprinkler body (which could result in high pressure). At 85 psi, the HES
sprinkler nozzle had a 54 percent lower flow rate than the standard sprinkler nozzle.
• The recommended operating pressure (45 psi) mimics conditions with pressure
regulation.38 The HES sprinkler nozzle had a 66 percent lower flow rate at 45 psi
compared to the standard sprinkler nozzle at peak tested pressure (85 psi).
Figure 6 also shows that, for standard sprinkler nozzles, the flow rate was reduced by 40
percent from maximum tested pressure (85 psi) to its recommended operating pressure (30
psi). For HES sprinkler nozzles, the flow rate was reduced by 27 percent between maximum
tested pressure (85 psi) and its recommended operating pressure (45 psi).39 In other words, the
percent difference in flow rate between maximum and recommended tested pressure was larger
for standard spray sprinkler nozzles than HES sprinkler nozzles.
Overall, Figure 6 shows that HES sprinkler nozzles had a lower flow rate over a wide range of
pressures compared to standard spray sprinkler nozzles.
It is important to note that the percentages reported above are not necessarily representative of
potential water savings. However, if the irrigated area is the same, the HES sprinkler nozzle will
apply less water than the standard sprinkler nozzle over the same length of time due to its lower
flow rate. In reality, the area irrigated by a single HES sprinkler nozzle is typically larger than
that of a standard sprinkler nozzle, making the potential savings even higher for retrofits.40
WaterSense invites stakeholders to share any additional performance data on HES
sprinkler nozzles.
VI. Product Marking, Documentation, and Marketing
WaterSense is considering requiring labeled spray sprinkler nozzle marking and documentation
to conform to all applicable sections of ASABE/ICC 802-2020, as listed below.
Section 304.1.5 of ASABE/ICC 802-2020, Sprinkler and Bubbler Product Marking, General
indicates that nozzles shall be individually marked and shall have markings identifiable when the
sprinkler is not in operation.
Section 304.1.2 of ASABE/ICC 802-2020, Marking of Sprays and Rotors indicates that
manufacturers are required to make information in Section 304 of the standard available to the
end user in a publicly available means. The following information from Section 304.2 of
ASABE/ICC 802-2020, Marking of Sprays and Rotors applies to spray sprinkler nozzles and
must be made publicly available:
• Flow rate at the minimum, recommended, and maximum operating pressure as
measured in Section 303.5.3 of the standard, in units of gpm;
38 Ibid.
39 Ibid.
40 Ibid.
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Specification for Spray Sprinkler Nozzles
WaterSense
• Distance of throw at the minimum, recommended, and maximum operating pressure as
determined in Section 303.5.4 of the standard, in units of feet;
• Spray pattern and the range of adjustability, as applicable;
• Design trajectory angle in units of degrees;
• Application rate at the minimum, recommended, and maximum operating pressure as
calculated in Section 303.6 of the standard, in units of inches per hour; and
• DU of the lower quarter results for each nozzle as defined in Section 303.6.2 of the
standard, expressed as a range ± 0.05 of the calculated DUlq.
For instances where flow rate, distance of throw, and/or application rate vary depending on the
nozzle selected, Section 304.2 allows manufacturers to provide a range or table.41
WaterSense proposes that certified products and/or their associated packaging or
documentation display the recommended and maximum operating pressure.
WaterSense is considering requiring the product packaging of WaterSense labeled spray
sprinkler nozzles to indicate whether the nozzle should be installed on a WaterSense labeled
spray sprinkler body with integral pressure regulation.
WaterSense invites stakeholder feedback on these proposed product marking and
documentation requirements.
VII. Estimated Water Savings
When WaterSense released the NOI for landscape irrigation sprinklers in 2014, it had not
identified any studies demonstrating water savings associated with HES sprinkler nozzles. The
only studies available (conducted by the Southern Nevada Water Authority [SNWA] and Eugene
Water and Electric Board [in Oregon]) did not measure savings. Since 2014, researchers have
published several studies demonstrating real-world water savings associated with HES sprinkler
nozzles (see Appendix A for details on the studies).
Based on these studies, WaterSense estimates that HES sprinkler nozzles have the potential to
use approximately 10 percent less water than standard spray sprinkler nozzles. This estimate is
a weighted average based on the number of landscapes in the savings studies in Appendix A.
The weighted average was heavily influenced by one study (conducted by the Metropolitan
Water District of Southern California) that had the largest number of landscapes. Many other
studies reported water savings close to, or exceeding, 20 percent. Although the weighted
average savings estimate is lower than WaterSense labeled products' typical water savings
percentage, WaterSense has developed specifications for other irrigation products with
estimated water savings below 20 percent (e.g., weather-based irrigation controllers) that may
still have national applicability and potential for significant water savings.
Assuming 10 percent savings, the average household could save approximately 2,400 gallons
of water annually by replacing standard spray nozzles with HES sprinkler nozzles. WaterSense
bases this figure on an average household outdoor water use of 50,500 gallons42 and
conservatively assumes that 50 percent of outdoor water use is attributable to spray irrigation.43
41 ICC. 2020. Op. tit.
42 DeOreo, William B., Peter W. Mayer, B. Dzigielewski and J. Kiefer. 2016. Residential End Uses of
Water, Version 2. Published by the Water Research Foundation. Table 6.32, Page 154.
43 Mecham, Brent. 2016. Personal communication.
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WaterSense
If the assumption is low, homes would likely experience greater savings from installing HES
sprinkler nozzles as a retrofit.
WaterSense is interested in feedback from stakeholders on whether the estimated
percentage of outdoor water used for spray irrigation is accurate, or whether spray
irrigation typically accounts for more than 50 percent of outdoor water use in residential
properties.
Based on WaterSense's current calculations, the average household could save approximately
$32 annually per landscape by replacing standard spray nozzles with HES sprinkler nozzles.
The payback period is 3 years and 5 months, which is comparable to the average product
warranty period for MSMT sprinkler nozzles.44 WaterSense uses product warranties as an
indicator for product lifespan in its calculations of payback period. However, homeowners likely
leave their spray sprinkler nozzles installed for much longer—typically until there is a problem—
rather than replacing them every three to four years. As a result, sprinkler nozzles may prove to
be more cost-effective in reality.
WaterSense is interested in stakeholder feedback on spray sprinkler nozzle replacement
behaviors. For example, do stakeholders typically replace nozzles after a designated
period of time, or do they wait until they need to fix malfunctioning spray sprinkler
nozzles in the event of a problem? Specifically, are there data indicating how long spray
sprinkler nozzles are installed in the field before being replaced, and/or how long spray
sprinkler nozzles typically last in residential settings?
VIII. Communicating Savings
WaterSense has identified application rates as the primary mechanism leading to water savings
with HES sprinkler nozzles. WaterSense suggests that application rate is a more appropriate
attribute than flow rate for the purposes of a potential WaterSense label, since the former
reflects the irrigated area, as well as the rate at which water is emitted from the sprinkler nozzle.
To understand the influence of application rate on water use by HES sprinkler nozzles, it is
useful to compare flow rate between WaterSense labeled showerheads and standard
showerhead models. WaterSense labeled showerheads have a lower flow rate than standard
models, but still provide adequate performance. Individuals are likely to shower for
approximately the same length of time regardless of the showerhead's flow rate, meaning that a
lower flow rate results in less water use. Similarly, even though HES sprinkler nozzles provide a
lower application rate to a landscape, homeowners are likely to maintain a similar irrigation
schedule after retrofitting their sprinkler nozzles, leading to water savings from the lower flow
rate. The lower flow rate also allows water to percolate into the soil, limiting runoff and water
waste.
It will be important to consider proper consumer messaging for HES sprinkler nozzles.
Researchers have speculated that water savings related to HES sprinkler nozzles may be
largely influenced by human behavior. Since HES sprinkler nozzles apply water at a lower rate,
irrigation systems should operate for longer periods of time (i.e., longer runtimes) to provide
sufficient water to the landscape. Typical homeowners likely program their irrigation controllers
44 EPA's market research found that the most common MSMT sprinkler nozzles on the market offer
warranties between 2 and 5 years.
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WaterSense
to provide more water than necessary for their landscapes, regardless of the type of spray
sprinkler nozzle installed or its precipitation rate. Since HES sprinkler nozzles generally have
lower flow rates than standard spray sprinkler nozzles, industry guidance recommends adjusting
irrigation schedules to increase the runtime to accommodate the lower precipitation rate
following a retrofit.
However, if a system is retrofitted with HES sprinkler nozzles and the schedule is not changed,
HES sprinkler nozzles will apply less water to the landscape due to their lower flow rates. This
may have occurred in many of the savings studies documented in Appendix A. If HES sprinkler
nozzles are installed on a new landscape accompanied by a new schedule, or if a retrofit is
implemented along with an alternative schedule that increases runtime, it is not currently known
whether HES sprinkler nozzles will apply less water than if the landscape had standard sprinkler
nozzles.
Although runtimes should be adjusted post-retrofit, some utilities and researchers suspect that
homeowners or irrigation contractors may not adjust their irrigation schedules accordingly. Even
if homeowners or contractors do adjust irrigation schedules for longer runtimes after installation,
it is possible that runtimes are not extended enough to offset the lower application rate from the
HES sprinkler nozzles, resulting in net water savings. One water utility WaterSense interviewed
noted that customers did not feel comfortable running their sprinklers for more than 30 minutes
due to extensive outreach about drought. The utility employee mentioned that these
homeowners felt guilty about watering their lawns for extended periods of time and instead
wanted to be seen as doing their part to respond to drought. If this is a widespread sentiment,
homeowners may see significant water savings from installing HES sprinkler nozzles, because
they will not be willing to irrigate for the longer time periods needed to supply the volume of
water to their landscapes that was provided by sprinklers with standard sprinkler nozzles.
Unfortunately, none of the savings studies discussed in Appendix A examined irrigation
schedules before and after retrofits, so WaterSense cannot determine if water savings are due
to lower flow rate alone, or if factors such as irrigation scheduling or other system adjustments
impacted the results.
WaterSense is interested in stakeholder feedback on suspected reasoning behind
potential water savings, including any information on whether stakeholders change
irrigation schedules after a retrofit. WaterSense invites stakeholder opinions on irrigation
runtimes, including preferences for duration of irrigation.
The influence of application rate on irrigation volume could also cause challenges with local
policies. During a discussion with WaterSense, one water utility manager suggested that some
regions might have watering windows (i.e., watering restrictions based on time of day). In those
locations, there may not be enough time to adequately water larger landscapes with HES
sprinkler nozzles. Some water utilities provide residents with a household water budget that can
be met over multiple days, avoiding the problem of insufficient time for irrigation. However, it is
possible that if municipalities enforce strict time windows for irrigation, residents with HES
sprinkler nozzles may not be able to water as long as necessary, even if the resident is
comfortable with a longer runtime.
WaterSense is interested in feedback from water utilities on promoting WaterSense
labeled HES sprinkler nozzles. In particular, WaterSense is curious whether water utilities
have concerns about whether consumers with HES sprinkler nozzles could meet their
irrigation needs with watering windows in place.
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IX. Summary of Information Requests
WaterSense welcomes stakeholder feedback on all aspects of this notice; summarized below
are the specific outstanding issues and questions about which WaterSense is seeking input
prior to drafting a specification for spray sprinkler nozzles. All interested parties are encouraged
to submit information and comments to watersense-products@erg.com.
Section II Technical Background
• WaterSense would like stakeholder input on its product category definition of "spray
sprinkler nozzle."
Section III Scope
• WaterSense would like stakeholder feedback on the intended scope of the
specification.
Section IV Water Efficiency and Performance
• WaterSense is seeking stakeholder feedback on its proposal to use application rates
(at recommended operating pressure and high pressure) as a water efficiency
criterion for spray sprinkler nozzles. WaterSense is also interested in whether any
manufacturers currently use the ASABE/ICC 802-2020 test method for application
rate and, if so, would be willing to share masked data with WaterSense.
• Additionally, WaterSense requests stakeholder opinions on using the following
parameters to evaluate spray sprinkler nozzles:
o Test each radius in a model's product family at the full circle pattern only; and
o Test models with an adjustable radius at the maximum radius.
• WaterSense seeks input on whether it should require spray sprinkler nozzles to have
matched precipitation to be eligible for the WaterSense label. What would be an
acceptable variance in application rates to ensure matched precipitation? If
WaterSense requires matched precipitation, how should EPA verify the data?
• WaterSense is interested in feedback from irrigation contractors about whether they
are likely to incorporate HES sprinkler nozzles in bids for new irrigation systems, any
factors that might influence their decision (i.e., new installation vs. retrofit), and
whether HES sprinklers reduce the cost of materials in practice.
• WaterSense seeks stakeholder feedback on whether ASAE/ASABE S398.1 is an
appropriate test method for distance of throw.
• Do stakeholders believe it is reasonable for WaterSense to require the tested
distance of throw to align with the value reported by the manufacturer? WaterSense
is also interested in stakeholder input on the appropriate percent exceedance (e.g.,
percentage greater than the rated distance of throw) to prevent water waste due to
overspray.
• WaterSense invites manufacturers to submit laboratory data on DU for HES and
standard spray sprinkler nozzles. WaterSense also invites manufacturers to indicate
whether they collect DU data in accordance with ASABE/ICC 802-2020 or through
another method.
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WaterSense® Notice of Intent to Develop a Draft
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WaterSense
• WaterSense would like stakeholder input on whether DU should be used in a
specification to establish a minimum level of performance or used to differentiate
HES and standard spray sprinkler nozzles.
• WaterSense invites stakeholders to submit data pertaining to the relationship
between DU and water savings and/or performance (e.g., landscape health).
• WaterSense invites stakeholders to share data on droplet size and water efficiency,
especially collected in accordance with ISO Standard 15886-2:2021. WaterSense
welcomes feedback on whether stakeholders think droplet size should be included
as a criterion in a WaterSense specification.
• WaterSense welcomes stakeholder feedback on whether to require the listed
sections of ASABE/ICC 802-2020 in a potential specification.
Section V Existing Performance Data
• WaterSense invites stakeholders to share any performance data on HES sprinkler
nozzles.
Section VI Product Marking, Documentation, and Marketing
• WaterSense invites stakeholder feedback on the proposed product marking and
documentation requirements.
Section VII Estimated Water Savings
• WaterSense is interested in feedback from stakeholders on whether the estimated
percentage of outdoor water used for spray irrigation is accurate, or whether spray
irrigation typically accounts for more than 50 percent of outdoor water use in
residential properties.
• WaterSense is interested in stakeholder feedback on spray sprinkler nozzle
replacement behaviors. For example, do stakeholders typically replace nozzles after
a designated period of time, or do they wait until they need to fix malfunctioning
spray sprinkler nozzles in the event of a problem? Specifically, are there data
indicating how long spray sprinkler nozzles are installed in the field before being
replaced, and/or how long spray sprinkler nozzles typically last in residential
settings?
Section VIII Communicating Savings
• WaterSense is interested in stakeholder feedback on suspected reasoning behind
potential water savings, including any information on whether stakeholders change
irrigation schedules after a retrofit. WaterSense invites stakeholder opinions on
irrigation runtimes, including preferences for duration of irrigation.
• WaterSense is interested in feedback from water utilities on promoting WaterSense
labeled HES sprinkler nozzles. In particular, WaterSense is curious whether water
utilities have concerns about whether consumers with HES sprinkler nozzles could
meet their irrigation needs with watering windows in place.
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EPA
WaterSense® Notice of Intent to Develop a Draft
Specification for Spray Sprinkler Nozzles
WaterSense
X. Schedule and Next Steps
WaterSense is requesting input, supporting information, and data from all interested parties on
topics discussed in this NOI and otherwise related to HES sprinkler nozzles. Interested parties
can provide input to WaterSense regarding any of the issues presented in this notice by
submitting written comments to watersense-products@erg.com. Comments and information on
the issues presented in this NOI are welcome and will be taken into consideration as
WaterSense considers development of a draft specification. The development and release of a
draft specification will be contingent on adequate resolution of questions and issues presented
in this NOI.
XI. References
A&N Technical Services, Inc. 2015. High Efficiency Nozzle Evaluation, Measurement, and
Verification FINAL DRAFT. Encinitas, CA.
ASABE. 1985. ASAE/ASABE S398.1 Procedure for Sprinkler Testing and Performance
https://elibrary.asabe.org/abstract.asp?aid=41295&t=3&dabs=Y&redir=&redirType=
Baum-Haley, Melissa. 2014. Evaluation of Potential Best Management Practices - Rotating
Nozzles. The California Urban Water Conservation Council. Sacramento, CA.
Berg, Joseph, Melissa Baum-Haley, and Thomas Chesnutt. 2012. Measured Water Savings and
Cost Effectiveness of Smart Timers and Rotating Nozzles. Poster presented at
WaterSmart Innovations Conference. Las Vegas, NV. October 3-5, 2012.
https://cereqportal.com/wsi/documents/poster sessions/2012/P-06.pdf
Bijoor, Neeta. 2019. Water Savings from Turf Removal and Irrigation Equipment Rebates.
Valley Water. San Jose, CA.
Bijoor, Neeta. 2021. Saving Water Wth a Landscape Water Conservation Rebate Program.
Journal of the American Water Works Association January/February 2021: 50-57.
https://doi.orq/10.1002/awwa. 1651.
Cardenas, B., M.D. Dukes, and N. Taylor. 2019. Irrigation Conservation Program Evaluation in
Orange County, Florida: Tasks 1, 2, and 3. University of Florida. Gainesville, FL.
Dukes, Michael D., Melissa B. Haley, and Stephen A. Hanks. 2006. Sprinkler Irrigation and Soil
Moisture Uniformity. Proceedings of the 27th Annual International Irrigation Show, San
Antonio, TX., November 5-7, 2006.
www, irrigation.org/IA/FileUploads/IA/Resources/TechnicalPapers/2006/Sprinklerlrrigatio
nAndSoilMoistureUniformity.pdf.
Dukes, Michael. 2021. Personal communication.
Reporting.
26
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EPA
WaterSense® Notice of Intent to Develop a Draft
Specification for Spray Sprinkler Nozzles
WaterSense
EPA. 2014. WaterSense Notice of Intent (NOI) to Develop a Draft Specification for Landscape
Irrigation Systems, https://www.epa.gov/sites/default/files/2017-01/documents/ws-
products-noi-irriqation-sprinklers.pdf.
EPA. 2017. WaterSense Specification for Spray Sprinkler Bodies, Version 1.0.
www.epa.gov/sites/default/files/2017-09/documents/ws-products-spec-ssb.pdf.
Hattendorf, Mary, and Mark A. Crookston. 2011. Catch Can Placement, Height, and Nozzle
Trajectory: Effects on Distribution Uniformity. Irrigation Association Technical Library.
www.irriqation.orq/IA/FileUploads/IA/Resources/TechnicalPapers/2011/CatchCanPlace
mentHeiqhtAndNozzleTraiectorvEffectsOnDistributionUniformitv.pdf.
ICC. 2020. ASABE/ICC 802-2020 Landscape Irrigation Sprinkler and Emitter Standard.
www.iccsafe.org/products-and-services/standards/is-iedc/.
ISO. 2021. ISO 15886-2: 2021 Agriculture irrigation equipment- Sprinklers.
www.iso.org/standard/77748.html.
Graham, Mark. 2016. High Efficiency Nozzle Evaluation, Measurement and Verification. Paper
presented at WaterSmart Innovations Conference. Las Vegas, NV. October 6, 2016.
https://ceregportal.com/wsi/documents/sessions/2016/T-1616.pdf.
Kieffer, Douglas L. and T. Sean O'Conner. 2007. Managing Soil Moisture on Golf Greens Using
a Portable Wave Reflectomoter. Paper presented at the 28th Annual Irrigation Show.
San Diego, CA. December 9-11, 2007. www.specmeters.com/assets/1/7/kieffer-
OConnor TDR300.pdf.
Kieffer, Douglas L. and Mike Huck. 2008. A Comparison of Fairway Distribution Uniformity
Computed with Catch Can Data and with Soil Moisture Data from Three Sampling
Depths. Paper presented at the 29th Annual Irrigation Show. Anaheim, CA. November 2-
4, 2008. www.specmeters.com/assets/1/7/Kieffer-Huck Abstract2197.pdf.
Kumar, Ramesh, and Eudell Vis. 2009. Effect of Rotary Nozzles and Cycle and Soak
Scheduling on Landscape Irrigation Efficiency. Irrigation Association Technical Library.
www.clca.org/wp-content/uploads/2017/11/Rotarv Nozzles and Cycle Soak.pdf.
Mecham, Brent Q. 2002. Comparison of Catch Can Distribution Uniformity to Soil Moisture
Distribution Uniformity in Turfgrass and the Impacts of Irrigation Scheduling. Northern
Colorado Water Conservancy District. Loveland, CO.
www.irrigation.org/IA/FileUploads/IA/Resources/TechnicalPapers/2002/ComparisonQfC
atchCanDistributionUniformitvToSoilMoistureDistributionUniformitvlnTurfgrassAndThelm
pactsOnlrrigationScheduling.pdf.
Petersen, J. 2012. Reducing Peak Hour Demand with MSMT-MPR Sprinkler Nozzle Retrofits.
Poster presented at WaterSmart Innovations Conference. Las Vegas, NV. October 3-5,
2012. https://ceregportal.com/wsi/documents/poster sessions/2012/P-28.pdf.
27
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EPA
WaterSense® Notice of Intent to Develop a Draft
Specification for Spray Sprinkler Nozzles
WaterSense
Petersen, J. 2013. Reducing Peak Hour Demand with Nozzle Retrofits: Three Year Evaluation.
Paper presented at WaterSmart Innovations Conference. Las Vegas, NV. October 3,
2013. www.pnws-awwa.org/uploads/PDFs/conferences/2014/Fridav%204.%20PNWS-
AWWA 2014 MSMT MPR.pdf.
Schein, Letschert, Chan, Chen, Dunham, Fuchs, McNeil, Melody, Stratton, and Williams. 2017.
Methodology for the National Water Savings and Spreadsheet: Indoor Residential and
Commercial/Institutional Products, and Outdoor Residential Products. Lawrence
Berkeley National Laboratory.
Solomon, K.H., J.A. Kissinger, G.P. Farrens, and J. Borneman. 2007. Performance and Water
Conservation Potential of Multi-Stream, Multi-Trajectory Rotating Sprinklers for
Landscape Irrigation. Applied Engineering in Agriculture 23(2): 153-163.
Sovocool, K., M. Morgan, and M. Drinkwine. 2009. Field Study of Uniformity Improvements from
Multi-Stream Rotational Spray Heads and Associated Products. Irrigation Association
Technical Library.
www.irrigation.org/IA/FileUploads/IA/Resources/TechnicalPapers/2009/FieldStudvQfUnif
ormitvlmprovementsFromMulti-StreamRotationalSpravHeadsAndAssociatedProducts-
PreliminarvResults.pdf.
Sovocool, K., M. Morgan, and M. Drinkwine. 2013. Observed Long-Term Results of Multi-
Stream Rotational Spray Heads and Associated Product Retrofits. Paper presented at
WaterSmart Innovations Conference. Las Vegas, NV. October 3, 2013.
Sovocool, K. 2014. SNWA Smart Sprinkler Study Follow-up. Unpublished. October 2014.
Vis, E, R. Kumar, and S. Mitra. 2007. Comparison of Distribution Uniformity of Soil Moisture and
Sprinkler Irrigation in Turfgrass. Project funded by the California Landscape Contractors
Association Environmental Research Funding Program.
Wascher, John. 2011. Multi-Stream, Multi-Trajectory Nozzles; How They Save Water, Labor
and Installation Costs. Irrigation Association Technical Papers.
www.irrigation.org/IA/FileUploads/IA/Resources/TechnicalPapers/2011/Multi-
StreamMulti-
TraiectoryNozzles(MSMT)AndHowThevSaveWaterLaborAndlnstallationCosts.pdf.
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WaterSense
WaterSense® Notice of Intent to Develop a Draft
Specification for Spray Sprinkler Nozzles
Appendix A. Water Savings Studies
Title
Year
Author (or who
conducted the
study)
Number of Landscapes Included in
Study
Savings
High Efficiency Nozzle Evaluation,
Measurement and Verification FINAL
DRAFT
2015
A & N Technical
Services, Inc.
2,175 single-family residences
171 high-use customers
Single-family residences: 7 percent
High-use customers: 38 percent
High Efficiency Nozzle Evaluation,
Measurement and Verification
2016
Mark Graham
Evaluation of Potential Best
Management Practices—Rotating
Nozzles
2014
Melissa Baum-
Haley
82 single-family residences
148 commercial customers
Single-family residences: 8 percent
Commercial customers: 11 percent
Measured Water Savings and Cost
Effectiveness of Smart Timers and
Rotating Nozzles
2012
Joseph Berg,
Melissa Baum-
Haley, and
Thomas Chestnutt
i
November 2022
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WaterSense
WaterSense® Notice of Intent to Develop a Draft
Specification for Spray Sprinkler Nozzles
Title
Year
Author (or who
conducted the
study)
Number of Landscapes Included in
Study
Savings
Water Savings From Turf Removal and
Irrigation Equipment Rebates
2019
Neeta Bijoor
40 single-family residences
20 percent
Saving Water With a Landscape Water
Conservation Rebate Program
2021
Neeta Bijoor
Irrigation Conservation Program
Evaluation in Orange County, Florida
2019
Bernardo
Cardenas, Michael
Dukes, and Nick
Taylor
34 single-family residences
17 percent
ii
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