EPA
Explanation of Performance Testing Under the
WaterSense Specification for Showerheads
WaterSense
Explanation of Performance Testing Under the
WaterSense® Specification for Showerheads
I. Introduction
The WaterSense label helps consumers identify products that offer both water efficiency and
performance. Performance is critical to ensure that consumers are satisfied with WaterSense
labeled products and continue to use them.
When more water-efficient plumbing products first entered the market, some were found to have
inferior performance compared to standard products. As a result, these products were not
widely adopted, limiting their overall water savings potential. Learning from this experience,
WaterSense includes performance criteria for all products it labels, allowing the program to
distinguish water-efficient products that perform as well or better than their standard
counterparts. When consumers purchase a WaterSense labeled product, they can be confident
that it will perform well and save water.
WaterSense evaluates showerhead performance through three key performance metrics:
•	Spray force
•	Spray coverage
•	Minimum flow rate (i.e., pressure compensation)
The testing procedures for each of these requirements are incorporated into the WaterSense
Specification for Showerheads by reference to the American Society of Mechanical Engineers
(ASME) A112.18.1/Canadian Standards Association (CSA) B125.1 Plumbing Supply Fittings
standard.
This document explains the performance testing requirements in the WaterSense Specification
for Showerheads, Version 1.1.
II. Background on Development of Performance Requirements
WaterSense developed the requirements and testing procedures for the three key performance
criteria included in the WaterSense Specification for Showerheads - spray force, spray
coverage, and minimum flow - based on consumer testing and through coordination with the
ASME/CSA Technical Committee on Plumbing Fittings.
During the development of the WaterSense Specification for Showerheads, Version 1.0,
consumers tested a variety of showerheads and provided feedback about their preferences for
different performance features. WaterSense worked with testing laboratories to translate the
user preferences into repeatable and reproducible test methods that could be evaluated by any
independent third-party certifying body.
WaterSense continues to coordinate with the ASME/CSA Technical Committee to align
requirements of the WaterSense Specification for Showerheads with ASME A112.18.1/CSA
B125.1. This cooperative relationship 1) engaged experts from the manufacturing, utility, and
certification communities; and 2) worked through an existing public process established in the
United States and Canada for developing standards and specifications for plumbing fittings.
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EPA
Explanation of Performance Testing Under the
WaterSense Specification for Showerheads
WaterSense
The collaboration has also facilitated the incorporation of rain showers in the WaterSense
Specification for Showerheads. As defined in ASME A112.18.1/CSA B125.1, rain showers are
showerheads mounted directly over the bather with the faceplate parallel to the floor. The
showerhead can be mounted on the ceiling or attached to an extended shower arm. Because of
the intended operation of this subcategory of showerheads, WaterSense worked with the
ASME/CSA Technical Committee to modify the spray force test protocol and criteria to
accommodate these products, while also ensuring an equivalent performance metric is met.
More information is provided below.
III. Spray Force
The spray force requirements were established based on the lower bounds of user satisfaction
reported in consumer testing. To be eligible for WaterSense labeling, showerheads must meet
the minimum force requirement as assessed with a testing apparatus. The force criteria are
intended to exclude showerheads whose spray force is less than that preferred by consumers.
As described below, the apparatus was originally designed for standard showerheads and has
been modified for rain showers.
The force test apparatus required in the WaterSense Specification for Showerheads, Version
1.0, depicted in Figure 1, was designed for standard showerheads that spray water at a 45°
angle from the wall. The center of the force target and the center of the showerhead faceplate
are aligned and 18 ± 0.25 inches (457 millimeters [mm] ± 6 mm) apart.
¦	
Figure 1. The spray force test protocol apparatus for standard fixed showerheads.
Once the water flow is initiated, the showerhead is adjusted only using its standard components,
such that the center of the spray pattern aligns with the center of the force target. In this
configuration, the shower spray is perpendicular to the force plate, as depicted in Figure 2. As a
result, the effective force of the spray equals the actual force required to move the force
balance. If the force of the spray equals or exceeds 2.0 ounces-force (ozf) [0.56 Newtons (N)], it
will cause the force gauge located between the force plate and the counterweight to register a
positive value. This indicates that the showerhead passes the 2.0 ozf criteria stipulated in the
specification.
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WaterSense
Explanation of Performance Testing Under the
WaterSense Specification for Showerheads
2 oz
Force Plate
Ground Surface
Figure 2. Visualization of the spray force test protocol apparatus for standard fixed showerheads. The
water spray hits the force plate at a 90° angle.
Version 1.1 of the WaterSense Specification for Showerheads updates the criteria to facilitate
testing of rain showers. The original requirements were not crafted to assess rain showers,
which have different spray mechanics than standard showerheads. The updated spray force
criteria for rain showers are mathematically equivalent to the criteria for standard showerheads
and make it possible for rain showers to be evaluated for WaterSense labeling.
Rain showers are intended to be mounted directly overhead and spray water vertically from the
ceiling, perpendicular to the floor. Flow from a rain shower mounted at a 45° angle, consistent
with the Version 1.0 test protocol depicted above, may not fully reach the force plate, since rain
showers primarily function by gravity and may have minimal horizontal force. As a result, many
rain showers were not able to meet the force requirements in Version 1.0 of the specification
and could not earn the WaterSense label. To account for rain showers' typical mounting
configuration and ensure consistent and equivalent testing requirements to standard
showerheads, EPA worked with the ASME/CSA Technical Committee to update the spray force
test protocol currently included in the ASME A112.18.1/CSA B125.1 standard.
To effectively measure the force of a rain shower, Version 1.1 of the WaterSense Specification
for Showerheads (by reference to the ASME A112.18.1/CSA B125.1 standard) allows rain
showers to be mounted vertically over the force plate in their intended mounting position. In this
mounting position, the water spray hits the force plate at a 45° angle, as opposed to a 90° angle
(see Figure 3).
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epa	Explanation of Performance Testing Under the
AA/atCl*ScUSC	WaterSense Specification for Showerheads
Force Plate
Ground Surface
Figure 3. Visualization of the test apparatus with a rain shower. The spray from the rain shower hits the
force plate at a 45° angle.
However, in this configuration, by simple geometry (shown on the left in Figure 4), the rain
shower would require an actual spray force of 2.8 ozf to move the counterbalance weight of 2.0
oz.1 WaterSense intends for rain showers to meet the same minimum spray force as standard
fixed showerheads (i.e., 2.0 ozf). Therefore, WaterSense has adopted the revised testing
protocol for rain showers outlined in the ASME A112.18.1/CSA B125.1 standard, but has
modified the effective force requirement. Using the same geometric relationships, an actual
force of 2.0 ozf will register an effective force of 1.4 ozf when hitting the force plate at a 45°
angle (shown on the right in Figure 4).2 Therefore, WaterSense has adjusted the counterweight
1 As determined using the following geometric relationship, where Xact is actual spray force:
Adjacent
cos(9) = 	
Hypotenuse
2
cos(45°) =	
%act
2
Xnr+
— = 2.8 ozf
cos(45°)
2 As determined using the following geometric relationship, where xeff is effective spray force:
Adjacent
cos(0) =
Hypotenuse
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WaterSense
Explanation of Performance Testing Under the
WaterSense Specification for Showerheads
to approximately 1.4 oz for a rain shower spray to meet the equivalent 2.0 ozf performance
criteria.
2.8 ozf
Actual
2.0 ozf
Effective
1.4 ozf
Effective
2 ozf
Actual
45'
45
Force Plate	Force Plate
Figure 4. Visualization of the actual and effective forces of a rain shower spray. If the spray achieves the
recommended minimum actual force of 2.0 ozf, the force plate will register an effective force of 1.4 ozf.
The new test protocol and performance criteria for rain showers are mathematically equivalent
to the protocol and criteria currently used to test standard fixed showerheads; this update simply
serves to equalize requirements for the two types of showerheads and reflect their typical
mounting configurations.
IV. Spray Coverage
WaterSense established spray coverage criteria because consumer test data showed general
dissatisfaction with showerheads that spray with a hollow spot in the center or that have too
much water flowing in the center to form a very narrow beam. The criteria contained in the
specification were crafted to identify and disqualify showerheads with sprays that are too wide
or too narrow.
The spray coverage component of the specification requires the use of an annular ring
apparatus consisting of a series of concentric rings, starting with a 2-inch diameter center ring
and each successive ring increasing in diameter by 2 inches out to 20 inches (see Figure 5).
The showerhead is positioned with its faceplate horizontal and parallel to a set of annular rings
so that the center of the annular rings is directly below the center of the showerhead's faceplate
(see Figure 6). When the showerhead's flowing pressure has stabilized, water flow is initiated
for at least 1 minute and water is collected in the annular rings. The relative amount of water
captured in each set of concentric rings represents the distribution of the spray pattern and can
be used to evaluate the showerhead's spray coverage.
cos (45°) = ^
xeff = 2 * cos(45°) = 1.4 ozf
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epa	Explanation of Performance Testing Under the
AA/atCl"SCTISC	WaterSense Specification for Showerheads
iOO	4.00 ttfii	IU( 10,00 1100
[50.W1I f|(l]j6tl| [153.40]	1354001 [»4.80| p.!M»| I40f..«| 14S7J0J
1-4.00
C.
Figure 5. a) A cross-section of the annular rings, b) A three-dimensional diagram of the annular rings, c)
A top-down view of the annular rings showing the spacing of each concentric ring. All dimensions are in
inches [millimeters (mm)] with a tolerance of ± 0.06 inches [1.6 mm]. The red dotted lines indicate optional
8-inch - 18inch rings.
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epa	Explanation of Performance Testing Under the
AA/atCl*ScUSC	WaterSense Specification for Showerheads
JL
L
An 18-inch rod may be used to
verify faceplate and annular ring
gage are parallel and centered.
18,0010.25
[457.20i6.35J
J0.00
[254.001
Figure 6. An illustration of the test configuration for spray coverage (shown in cross-section). The center
of the showerhead is directly above the center of the annular ring apparatus.
Following operation of the showerhead, the volume of water collected in each annular ring is
measured. The total volume of water collected by all annular rings is compared to the volume
predicted by the flow rate and duration of water flow. If the difference is greater than ±5 percent,
the test procedure is repeated.
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EPA
Explanation of Performance Testing Under the
WaterSense Specification for Showerheads
WaterSense
To satisfy the spray coverage criteria, the total combined maximum volume of water collected in
the 2- and 4-inch annular rings must not exceed 75 percent of the total volume of water
collected. This ensures that the showerhead spray coverage is not too narrow. Additionally, the
total combined minimum volume of water collected in the 2-, 4-, and 6-inch annual rings must
not be less than 25 percent of the total volume collected, indicating that the showerhead does
not provide spray coverage with a hollow center. The spray coverage criteria are intended to
ensure that water flow is distributed in a way consistent with user preference, as indicated by
consumer test data.
V. Minimum Flow Rate
WaterSense has stipulated requirements for minimum flow rates to ensure consistent water flow
across various household water pressures. Minimum flow requirements ensure that
WaterSense labeled showerheads will meet consumer performance expectations by meeting or
exceeding minimum flow rates, even in households with low water pressure. This showerhead
feature is known as pressure compensation.
To earn the WaterSense label, a showerhead's minimum flow rate is required to be greater than
60 percent of the maximum flow rate when tested at a flowing pressure of 20 ± 1 psi, and
greater than 75 percent of the maximum flow rate when tested at flowing pressures of 45 and 80
± 1 psi. WaterSense requires testing at 45 psi so consumers can match showerheads with
compatible automatic-compensating mixing valves, which are rated at 45 psi. The 20 ± 1 and 80
± 1 psi requirements are intended to evaluate flow rate under minimum and maximum flowing
pressures.
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