Water Sense

WaterSense® Draft Specification for Soil Moisture-Based
Irrigation Control Technologies

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WaterSense

WaterSense Draft Specification for
Soil Moisture-Based Irrigation Control Technologies

WaterSense® Draft Specification for Soil Moisture-Based
Irrigation Control Technologies

1.0 Scope and Objective

This specification establishes the criteria for soil moisture-based irrigation control technologies
labeled under the U.S. Environmental Protection Agency's (EPA's) WaterSense program. It
applies to stand-alone controllers, add-on devices, and plug-in devices that inhibit or allow an
irrigation event based on a reading(s) from a soil moisture sensor mechanism (i.e., sensor
mechanism). The EPA is defining this product category as follows, based on the definitions of
the applicable components included in the American Society of Agricultural and Biological
Engineers (ASABE) S633 Testing Protocol for Landscape Soil Moisture-Based Control
Technologies:1

•	Soil moisture-based irrigation control technology—a sensor mechanism and interface
device that enables or disables an irrigation event at preset or selected soil water values.
These products are commonly known as, and for the purpose of this specification shall
be referred to as, soil moisture sensors (SMSs).

•	Sensor mechanism—the portion of the device that contacts the soil and measures
physical properties that are related to water content or potential.

•	Interface device—the portion of the device that either enables/disables irrigation events,
and/or transmits soil water information to a control system for irrigation decision-making.
The interface device could be part of an irrigation controller or can be a separate
component, either integrated into or separate from the sensor mechanism.

The performance criteria contained in this specification are designed to test the capability of the
SMS, when programmed and operated in accordance with the manufacturer's instructions, to
successfully enable or disable an irrigation event based on soil moisture readings.

This specification applies to SMSs for use in residential or commercial landscape irrigation
applications.

The specification does not apply to:

•	On-demand SMSs, or those that automatically adjust irrigation schedules based on soil
water values.

•	Sensor mechanisms alone (i.e., sold without an interface device).

•	SMSs intended for use exclusively within agricultural irrigation systems.

2.0 Performance Criteria

SMSs shall be tested in accordance with the relevant sections of ASABE S633, as modified in
Section 2.1, and shall meet the performance criteria outlined in Section 2.2.

1 WaterSense intends to require soil moisture-based irrigation technologies to be tested in accordance
with ASABE S633 Testing Protocol for Landscape Soil Moisture-Based Control Technologies upon the
standard's final publication. This standard is currently undergoing public comment and final review.

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2.1	Testing modifications to ASABE S633

2.1.1	For add-on or plug-in devices, the interface device shall be connected to
a base controller, as described in Appendix A.

2.1.2	SMSs shall only be tested in the moderately coarse test medium and
water with an electrical conductivity (EC) of 3 dS/m, as defined in ASABE
S633.

2.1.3	The freeze test shall be conducted in the 40 percent water depletion
container using the moderately coarse medium after the initial test is
complete.

2.2	Performance criteria

2.2.1	When tested in accordance with Section 6 of ASABE S633, as modified in
Section 2.1 of this specification, SMSs shall meet the following
performance criteria:

2.2.1.1	Each SMS evaluated shall enable and disable irrigation at each of
the three depletion levels.

2.2.1.2	The relative average deviation (RAD) of the readings at which the
replicate SMSs enable and disable irrigation, calculated in
accordance with Equations 1 and 2 below, when averaged across
all water depletion level readings, shall be less than or equal to 10
percent.

Equation (1)	Relative Avg Deviation = Avg De^iatlon

Where: x is the mean

Equation (2)	Avg Deviation = ^'=1^ *'^

Where: x is the mean

Xj is the observation
n is the number of observations

2.2.1.3	The absolute value of the slope of the line generated by plotting
irrigation enable readings for all three replicates across all three
depletion levels and the absolute value of the slope of the line
generated by plotting irrigation disable readings for all three
replicates across all three depletion levels shall both be greater
than zero when rounded to two significant digits (i.e., > 0.01).

2.2.2	When tested in accordance with Section 7.2 of ASABE S633, as modified
in Section 2.1 of this specification, each SMS evaluated shall enable and
disable irrigation after the sensor mechanism is placed in a freezer for
three days and thawed to pre-freeze medium temperature.

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3.0 Supplemental Capability Requirements

Add-on and plug-in devices, configured for testing in accordance with Appendix A, and stand-
alone controllers shall meet the following requirements in both soil moisture mode and standard
mode:

3.1	Be capable of preserving the contents of the irrigation program and sensor
mechanism settings when the power source is lost and without relying on an
external battery backup.

3.2	Either be capable of independent, zone-specific programming or storing a minimum
of three different programs to allow for separate schedules for zones with differing
water needs.

3.3	Be capable of indicating to the user when it is not receiving sensor mechanism input
and is not adjusting irrigation based on soil moisture content in the landscape.

3.4	Be capable of interfacing with a rainfall device.

3.5	Be capable of accommodating watering restrictions as follows:

3.5.1	Operation on a prescribed day(s)-of-week schedule (e.g., Monday-
Wednesday-Friday, Tuesday-Thursday-Saturday; any two days; any
single day).

3.5.2	Either even day or odd day scheduling, or any day interval scheduling
between two and seven days.

3.5.3	The ability to set irrigation runtimes to avoid watering during a prohibited
time of day (e.g., between 9:00 a.m. and 9:00 p.m.).

3.5.4	Complete shutoff (e.g., on/off switch) to accommodate outdoor irrigation
prohibition restrictions.

3.6	Include a percent adjust (water budget) feature.2

3.7	Be capable of reverting to a percent adjust (water budget) feature if the sensor
mechanism signal is lost.

3.8	Be capable of allowing for a manual operation troubleshooting test cycle and shall
automatically return to soil moisture mode within some period of time as designated
by the manufacturer, even if the switch is still positioned for manual operation.

4.0 Packaging and Product Documentation Requirements

SMSs shall be packaged and provided with documentation as indicated in this section.

2 The percent adjust (water budget) feature is defined as having the means to increase or decrease the
runtimes or application rates for zones by means of one adjustment without modifying the settings for
each individual zone.

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4.1	Stand-Alone Controllers

The product shall not be packaged nor marked to encourage operation of the controller in
standard mode. Any instruction related to the maintenance of the product shall direct the user
on how to return the controller to soil moisture mode.

4.2	Add-on and Plug-in Devices

Add-on and plug-in devices are not required to be packaged with the base controller(s) with
which they were tested or have been determined compatible, as specified in Appendix A.
However, the product documentation for the add-on and plug-in devices shall list each
compatible base controller model. The documentation shall also contain a statement to the
effect that the device is only WaterSense labeled when used in combination with a base
controller on the provided compatibility list.

5.0 Effective Date

This specification is effective on [TBD],

6.0 Future Specification Revisions

The EPA reserves the right to revise this specification should technological and/or market
changes affect its usefulness to consumers, industry or the environment. Major revisions to the
specification shall be made following input from industry partners and other interested
stakeholders.

7.0 Definitions

Definitions within ASABE S633 Testing Protocol for Landscape Soil Moisture-Based Control
Technologies are included by reference. The following definitions are additional terms that are
referenced in the specification:

Add-on device: An SMS in which the interface device is separate from the controller (either a
separate component or part of the sensor mechanism). It communicates the sensor mechanism
readings to a base controller (typically a standard clock-timer controller). For purposes of this
specification, add-on devices are defined as those that are designed to work with multiple
brands of base controllers.

Base controller: The irrigation controller to which the add-on or plug-in device is connected for
full operation. Mostly commonly, a base controller is a standard clock-timer controller.

Plug-in device: An SMS in which the interface device is separate from the controller (either a
separate component or part of the sensor mechanism). It communicates the sensor mechanism
readings to a base controller (typically a standard clock-timer controller). For purposes of this
specification, plug-in devices are defined as those that are designed to work specifically with
one brand of controller.

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Rainfall device: A device that either senses or measures rainfall to reduce or interrupt irrigation
in response to rain events. For the purpose of this specification, this includes, but is not limited
to, rainfall interrupt devices and tipping bucket rain gauges.

Stand-alone controller: An SMS in which the interface device is integrated into the controller.
This includes a single controlling device (i.e., the irrigation controller) and the sensor
mechanism(s) that provide the soil moisture data.

Soil-moisture mode: The operating mode in which the stand-alone controller, or plug-in and add-
on device and associated base controller, is using readings from the sensor mechanism to
modify the irrigation schedule.

Standard mode: The operating mode in which the stand-alone controller, or plug-in and add-on
device and associated base controller, is not using readings from the sensor mechanism to
modify the irrigation schedule.

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Appendix A: Testing Configuration and Compatible Base Controller

Determination

The requirements of this appendix apply to add-on or plug-in devices.

1.0 Initial Configuration for Testing

The manufacturer shall specify a base controller model with which the add-on or plug-in device
shall be connected and tested. Together, the unit shall be capable of meeting the requirements
of this specification, including the supplemental capability requirements specified in Section 3.0.

2.0 Determining Additional Compatible Base Controllers

If desired, additional base controller models with which the add-on or plug-in device can be
paired, and that together as a unit meet the requirements of this specification, including the
supplemental capability requirements specified in Section 3.0, can be identified.

The add-on or plug-in device is not required to be tested with the additional base controllers
determined to be compatible; however, any compatible base controllers shall communicate with
the interface device in the same way as the base controller with which the add-on or plug-in
device was tested (e.g., common wire interrupt).

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Appendix B: Informative Annex for WaterSense Labeling

The following requirements must be met for SMSs to earn the WaterSense label.
1.0 WaterSense Partnership

The manufacturer of the SMS must have a signed WaterSense partnership agreement in place
with the EPA.

2.0 Conformity Assessment

Conformance to this specification must be certified by a licensed certifying body accredited in
accordance with the WaterSense Product Certification System.

3.0 WaterSense Labeling

3.1	For add-on devices and plug-in devices, only the devices certified to meet the
requirements of this specification may bear the WaterSense label. Base controllers
with which the add-on or plug-in devices are tested and/or determined to be
compatible with shall not bear the WaterSense label. Product documentation shall
indicate that the add-on or plug-in device is only WaterSense labeled when used in
combination with the base controller(s) listed in product documentation described in
Section 4.0 of this specification.

3.2	Base controllers that are tested, or determined to be compatible with an add-on or
plug-in device, may bear the WaterSense promotional label and include language
similar to "Look for the WaterSense labeled [plug-in or add-on device] to improve the
water efficiency capabilities of this controller." See the WaterSense Program Mark
Guidelines for more information about the use of the WaterSense promotional label.

4.0 Product Sampling for Certification

SMSs shall be sampled and selected for testing in accordance with Section 5.1 of ASABE S633
(i.e., each test shall consist of three SMSs per manufacturer model randomly selected from a lot
of at least 10 items supplied by the manufacturer).

EPA

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