Smart Watering With
Irrigation Controllers
To promote water-smart irrigation, many landscapes feature a weather-based irrigation
controller (WBIC). WBICs use current local weather data to adapt landscape irrigation
schedules, only watering plants when they need it. The U.S. Environmental Protection
Agency's (EPA's) WaterSense® program labels WBICs that have been independently certified
to meet performance criteria detailed in the WaterSense Specification for Weather-
Based Irrigation Controllers. Replacing a standard clock timer with a WaterSense labeled
irrigation controller can save an average home thousands of gallons of water annually. This
document summarizes the benefits of WaterSense labeled WBICs, explains how they work,
and describes the additional features they have.
At the core of an irrigation system is the controller or
timer, where irrigation schedules are set, determining
the amount of water applied to the landscape. The
controller or timer is the key interface between the
irrigation system and end user in charge of operating
that system. Homeowners and irrigation professionals
can control when and how much water is applied to
the landscape using controllers or timers.
In addition to water savings, WaterSense labeled
controllers also provide a level of convenience,
reducing the need to change irrigation schedules to
continually match plant water needs as the seasons
change. Furthermore, many labeled controllers
provide the additional convenience of app-based
interfaces, allowing users to view water amounts
and control irrigation right from their mobile devices.
This added convenience allows consumers to track
their irrigation water use, increasing their awareness
of how much water they use outdoors. Additionally,
several labeled models integrate their app-based
software into smart homes systems, adding the option
of remote control over watering times.
Benefits of WaterSense Labeled
A properly designed, installed, and maintained
irrigation system can provide the right amount of
water across a landscape, ensuring water efficiency
and curb appeal. The controller is the brain behind
any good system. In particular, WaterSense labeled
weather-based irrigation controllers:
•	Provide a healthy, beautiful landscape:
WaterSense labeled controllers help landscapes
flourish and remain healthy by customizing
irrigation times for each different plant zone to only
provide plants the water they need,
•	Save money: WaterSense labeled controllers
help users reduce overwatering and may lower
water expenses. Products are available at a
variety of price points and are often incentivized
by water utility rebate programs
•	Reduce water waste: WaterSense labeled
controllers avoid unnecessary watering and
decrease the amount of water running off the
landscape, helping to reduce the amount of
pollution flowing to local waterways.
Photo (above left) courtesy of Hunter Industries Incorporated.
PHONE (866) WTR-SENS (987-7367) WEBSITE EMAIL watersense@epa.sov May 2020

• Provide convenience: Properly programmed
WBICs save users the time and effort required to
keep current on the weather and adjust watering
schedules, App-based products provide the added
convenience of monitoring and controlling water
use from mobile devices, whether onsite or from
How Do WaterSense Labeled WBICs
WaterSense labels WBICs that create or modify
irrigation schedules based on evapotranspiration (ET)
principles, which are a function of weather conditions
and plant type. ET is the quantity of moisture that
is both transpired by a plant (i.e., the water vapor
released from its leaves) and evaporated from the
soil and plant surfaces. WaterSense labeled WBICs
develop or adjust irrigation schedules based on
attributes in the landscape (e.g., plant type, soil type,
slope) and local weather. The data that determine
when the system will water are provided either by a
weather sensor located on the landscape, or via a
signal from a nearby weather station. As a result,
WBICs automatically reduce the watering times or
days when less water is needed, typically during the
cooler months or when rainfall is plentiful.
WaterSense labeled WBICs come in a variety of
models that range in price, complexity and capacity.
Models range from those that are intended for small
residential landscapes to those that can control
large commercial landscapes' watering systems.
Stand-alone controllers can replace an existing
controller or be installed in a new irrigation system,
as they provide all scheduling capabilities. Add-on
and plug-in devices connect to standard clock timer
controllers. These devices can be installed to upgrade
an existing irrigation controller, providing the weather-
based watering feature to an existing system. They
could also be paired with a new, compatible standard
clock timer controller and installed in a new system, or
replace a controller in an existing system.
WaterSense even labels WBICs that can be attached
to a hose bibb instead of an entire system, bringing
weather-based control to landscapes with only
one or two zones that are typically watered with
microirrigation, such as gardens, trees, or shrub beds.
Similar to WBICs that control in-ground irrigation,
users can program their landscape attributes, which
when combined with weather data, provides the right
amount of water only when plants need it.
One important
aspect of labeled
controllers pertains
to where their
weather data
come from—onsite
weather sensors
and/or weather
signals from local
weather stations.
Onsite sensor-
based controllers use real-time measurements
of locally measured environmental variables (e.g.,
temperature, humidity, solar radiation) to adjust
irrigation scheduling. An onsite sensor-based system
can also store historic weather information, which it
can use to modify the expected irrigation requirement
for the day or calculate onsite ET for the landscape. In
contrast, signal-based controllers receive a regular
signal of weather data from local weather station(s)
to update the watering schedule for the controller. For
example, if the weather is cool and damp, scheduled
runtimes may be shortened or eliminated by the
controller. Or if rain is predicted, some controllers will
withhold irrigation until the following day.
Additional Features Enhance
Photo courtesy of Rain Bird Corporation.
Onsite weather sensor. Photo courtesy of
Hunter Industries Incorporated.
WaterSense labeled controllers have many
capabilities that allow them to be water-efficient,
including the following features:
Irrigation program information and settings are
retained in the controller's memory when the

Better Control Is Just One
Piece of the Puzzle
While a WaterSerise labeled controller can
help reduce unnecessary watering, a holistic
approach to landscaping and irrigation is
required to achieve the full potential of water
Many homes' irrigation
systems operate at a
water pressure that is	J j.- - '
too high for sprinkler	~"
nozzles and can lead
to excessive irrigation
flow rates, misting, fogging, and uneven
coverage. Install WaterSense labeled spray
sprinkler bodies to regulate system pressure
at the sprinkler nozzle.
Utilize microirriaation in flower beds and
other non-turf areas to deliver water directly
to the root zone of plants, where it is needed
most, preventing runoff and reducing
Choose a portion of your yard to be a water-
smart landscape. Plants that are adapted to
your specific climate can reduce the need for
supplemental irrigation.
• Select an irrigation professional certified by
a WaterSense labeled program to assist with
designing, installing, maintaining, or auditing
your system to maximize water efficiency.
power source is lost and no backup battery is
Irrigation can be customized on landscapes
that have multiple zones with various watering
•	Alerts tell the user if the controller is not operating
in smart mode (e.g., if there is a problem with the
signal or local sensor input that stopped it from
automatically adjusting irrigation).
Because multiple states in certain climate regions
have mandated rain sensors, the controller must
be able to connect to them.
•	To comply with local utility mandates, the
controller must be able to accommodate watering
•	A water budget feature (also known as "percent
adjust") allows users to adjust water applied to the
landscape without changing the detailed settings
in the controller's program.
If the product loses real-time weather input or a
weather signal, it can use a proxy of historical
weather data or the percent adjust/water budget
If the user runs a manual troubleshooting test
cycle, the controller will automatically return to
smart mode within a specified time period as
designated by the manufacturer.
A searchable list of WaterSense labeled controllers,
their attributes, and compatible base controllers
(where applicable) is available on the WaterSense
Installing a Controller
Manufacturers include instructions for installing
WBICs within the product packaging, and many
are also available online. Most manufacturers also
provide training on
the installation and
operation of their
irrigation controllers
for professionals
and homeowners
to learn more about
installing these
products. Contact
your local irrigation
products distributor
or home improvement retailer to find a class in your
area. Contractors can become certified irrigation
professionals through programs that have earned
the WaterSense label; find a professional certifying
organization near you.
While WaterSense recommends that a certified
irrigation professional install and program WBICs,
many WaterSense labeled controllers are available
in big box stores in regions where in-ground irrigation
is prevalent or online, allowing a homeowner
to purchase a labeled controller and install it
themselves. Installation for these products is typically
straightforward in a few steps, but remember the
following tips:
Photo courtesy of Hunter Industries

•	Always follow the manufacturer's instructions.
•	After initial installation, closely monitor the
landscape for a few weeks and adjust the
controller if the landscape is too wet or too dry.
•	To realize full savings from an efficient irrigation
schedule, ensure the system is functioning
properly—no overspray, broken sprinklers, or
Programming for Water Savings
Correctly programming the controller is necessary
to achieve water savings. Many controllers have
default settings to water plants at levels that meet 100
percent of a plant's theoretical water needs. These
theoretical water needs focus on maximizing crop
yield. Landscape plants, however, should be treated
differently than crops, because a landscape typically
reflects a mixture of plant species with varying
vegetation density and microclimates. Most plants
will require less than their theoretical water needs
to maintain proper health and appearance. Thus, a
WBIC can be adjusted to better reflect the plant's
actual water needs.
The "percent adjust" or "water budget" feature present
on all WaterSense labeled controllers is a simple way
to adjust the amount of water that is applied to the
landscape. This feature should be a simple dial or
button to increase or decrease the water applied to a
specific irrigation zone.
Maintaining Savings
Once a WaterSense labeled controller is installed
and programmed, the controller automatically takes
care of seasonal weather adjustments, thereby not
requiring constant monitoring. However, no irrigation
control system should be installed based on "set
it and forget it." Contractors or users will need to
periodically inspect the landscape to ensure that
the irrigation system is performing properly. This
is especially important after installation. End users
should typically spend a couple of weeks monitoring
their landscape after a labeled controller is installed.
If it looks lush and green, watering can be reduced
using the water budget feature on the controller.
Users should continue to adjust the controller's water
budget feature until they find a balance that is both
water-efficient and healthy for their plants.
Many WaterSense
labeled controllers
provide water use
information to the end
user on smart phones
or other mobile devices.
This allows end users to
compare water use from
season to season and change behavior, irrigation
products, or landscape attributes to maximize water
savings. While some labeled controllers estimate
water use based on runtimes and estimated
precipitation rates of sprinklers, others are compatible
with flowmeters, providing actual measured water use
data to the end user.
For more information about WaterSense labeled
WBICs, visit
Above image courtesy of Rain Bird
For more information about
smart outdoor water use, visit