IRRIGATION CONTROLLERS 

TIMERS FOR THE HOMEOWNER 

Recommended Water Saving Features 

Water—too precious to waste! Water—too precious to waste!

IRRIGATION CONTROLLERS

TIMERS FOR THE HOMEOWNER

Recommended Water Saving Features

While controllers come in all types of shapes and sizes, the most important features 

are how well they can be programmed to handle diverse landscape and weather conditions. 

Disclaimer 

This booklet was originally developed by the East Bay Municipal Utility District 

(EBMUD), Oakland, California and is being published by EPA with EBMUD’s 

permission for informational purposes only. EPA publication does not constitute an 

endorsement of any products or services identified in the booklet, nor of EBMUD. 

Preface 

The U.S. Environmental Protection Agency published this booklet because of the 

importance that efficient landscape water use has for the environment and the economy. 

The most obvious benefit of efficient landscape water use is conservation of water 

resources. In most situations the water we use to irrigate landscapes is treated drinking 

water. By reducing the amount of drinking water used for landscape irrigation, we 

reduce the burden on water treatment facilities and often can defer future facility costs. 

A small but growing number of municipalities have reduced drinking water facility 

needs by building a separate water reuse system to supply reclaimed wastewater to 

homeowners for landscape irrigation and other non-potable uses. In either case, irrigation water should be used efficiently. This booklet is designed to help the homeowner 

understand and select the right controller for their individual needs and use it properly— 

the key to efficient irrigation. 

Efficient landscape water use can have many environmental and economic benefits: 

• Lower water bills from reduced water use.

• Extended life for water system infrastructure (e.g. treatment plants, pipe systems),

thus reduced taxpayer costs. 

• Reduced runoff of storm water and irrigation water that carries topsoil, fertilizers, 

and pesticides into lakes, rivers, and streams. 

• Conservation of natural resources and preservation of habitat for plants and wildlife

such as fish and waterfowl. 

• Decreased energy use (and air pollution associated with its generation) because less 

pumping and treatment of water is required. 

Acknowledgement 

Special recognition goes to Dick Bennett and Richard Harris of the East Bay Municipal 

Utility District for their efforts in producing this booklet. 

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This brochure is a cooperative effort sponsored by members of both the water and landscape industry to promote efficient landscape water use. The purpose of this brochure is 

to highlight important features of a controller (also called a timer or clock) that allow 

for proper watering schedules. Since many people are somewhat mystified or intimidated by these devices, hopefully, this brochure will help when making the decision of 

which controller to obtain. The main point to keep in mind is that the key to watering efficiently is to obtain a controller that can handle diverse landscape and 

weather situations and then to program it properly. This message is so important; 

it is repeated again in the text. 

Also discussed in this brochure is information on a new generation of controllers, 

called ET based controllers, that automatically change water schedules based upon 

past or historic climate conditions for a given region. 

We encourage you to contact your local water agency or landscape company to obtain 

more information on how to improve landscape water use efficiency. For any technical 

assistance you may need with your controller, contact the manufacturer. 

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Foreword 

Importance of Irrigation Controllers 

A large part of our household water use goes to watering our landscape and many 

households rely on automatic in-ground irrigation systems to accomplish this. One of 

the most important components of an automatic in-ground irrigation system is the irrigation controller (also called a timer or clock). The controller turns the automated irrigation system on and off at the times you select. In other words, the controller controls 

the irrigation system and you control the controller. Having a controller with certain minimum performance capabilities is vital to efficient watering. The right controller, properly scheduled, can result in significant water savings and lower water bills. 

While controllers come in all types of shapes and sizes, the most important features are 

how well they can be programmed to handle diverse landscape and weather conditions. 

How Does a Controller Work? 

An automatic in-ground irrigation system is a collection of pipes, tubing, valves, sprinkler heads, and circuitry used to irrigate a landscape. Automatic valves (also called stations or zones), which control the flow of water to different parts of the landscape, open 

and shut upon a signal from the controller. For example, there may be one valve that 

controls the water flow to some groundcover, another valve for some shrubs and another 

valve for the lawn. Once programmed, the controller determines when, how often, and 

how long each valve is open. It controls how much water goes where and when in 

your landscape based upon your instructions. The more programming flexibility 

the controller has, the more efficiently water can be applied to the landscape. 

Why Certain Controller Features are Important 

The key to watering efficiently is to obtain a controller that can handle diverse 

landscape and weather situations and then to program it properly to meet your 

plants’ water needs. Let’s imagine you have a front yard with three valves that control 

the water flow to a sloped lawn area, to several trees, and to a groundcover area. You 

desire to water the lawn every third day for the entire month in three short time intervals 

of five minutes each and want a 30-minute break between watering to avoid runoff from 

the slope. You also desire to water the trees, which are on a drip system, once a month 

for two hours. Next, you want to water the groundcover once a week for 30 minutes. 

Finally, you don’t want to water if it is raining. To accomplish this, your controller 

would need the following features: 1) three independent programs, 2) 120 minute station 

run times, 3) three start times per program, 4) interval program capability to 30 days, 

and 5) rain shut-off device capability (the actual rain shut-off device needs to be 

purchased separately). 

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Important Water Saving Features 

The recommended minimum hardware features for a controller include: 

• Three independent programs 

• Station run times from 1 to 200 minutes 

• Three start times per program 

• Odd/even, weekly and interval program capability up to 30 days 

• Water budgeting from 0-200%, in 10% increments, by program 

• 365 day calendar, adjusted for leap year 

• Non-volatile memory or battery back-up 

• “Off”, “Auto”, and “Manual” operation modes without disturbing programming 

• Rain shut-off device capability 

• Diagnostic circuitry to notify homeowner when station is shorted or a power 

failure has occurred 

The above features, discussed in more detail below, are important because they give you 

the ability to properly manage your landscape watering. 

Multiple independent programs allow watering different parts of the yard on different 

days. Station run times determine the upper and lower limit on how long an area can 

be watered. While watering times are usually in minutes, a few controllers are capable 

of assigning run times in seconds (for potted plants) and hours for drip applications. 

Multiple start times allow for repeat watering in the same area on the same day. 

Odd/even, weekly, and interval program capability allows for flexibility in deciding 

what days to water. For example, a 30-day calendar would allow watering a large tree 

once a month. Water budgeting (also known as a percent switch) allows for an increase 

or decrease in station run times by a certain percent. For example, during a cool spell, 

you may want to decrease watering time by 10% for all programs. This feature allows 

for the changing of all station run times within a given program in one easy step. 365­

day calendar allows for the tracking of the number of days in each month throughout 

the year. Non-volatile memory retains the set program in case of a power failure. 

However, the set start watering times are still affected. For example, a four-hour power 

failure where the watering times are set to start at 6 a.m. would result in 10 a.m. start. A 

battery back-up is recommended to retain the 6 a.m. watering time. Controllers with 

only volatile memories would both lose their set program and have the watering start 

time affected. For controllers with volatile memories, a battery back-up would retain 

both the set program and the set watering times. Rain shut-off device capability (and 

rain shut-off device) is used to automatically override the call for water during rain 

events. (The actual rain shut-off device needs to be purchased separately since it is not 

included with the controller.) Diagnostic circuitry to notify the homeowner when a station is shorted or a power failure has occurred is useful so that the controller can be 

checked for any changes or problems as soon as possible. 

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In addition to the above hardware, programming instruc-tions, technical support phone 

numbers, and irrigation scheduling information are important resource tools. 

Check with your local water utility, irrigation supply company, or landscape professional 

for local watering guidelines. 

Optional Controller Features 

Besides the above mentioned recommended controller features, several desirable but 

optional features include “pause times” and “soak cycles”. The “pause time” feature 

allows for some time to elapse before watering different stations within a program. This 

feature allows time for a control valve to completely close before the next valve opens 

ensuring more uniform pressure and thus better uniformity of coverage. For those on 

well water, this feature may allow time for the level in the well to recover before the 

next irrigation cycle. The “soak cycle” allows for short, multiple watering cycles. This 

feature can be used either before a normal irrigation cycle to reduce runoff or for multiple, short waterings of a given area. 

Controller Warranty 

Ask about the warranty on any controller you are considering. The length of a product 

warranty is often linked to quality and many controller manufactures are offering 

warranties in the 2-5 year range: the longer, the better. 

Other Important Components of an Efficient Irrigation System 

Besides obtaining an irrigation controller with the recom-mended features, there are 

other irrigation components that should be used with irrigation systems to save additional 

water. Control valves control the flow of water to different parts of the landscape and are 

used for the separate watering of plants with different watering needs. Check valves can 

be installed in sprinkler heads to prevent water from draining out of the irrigation line 

when the water is turned off and are most useful on sloped landscapes. Rain shutoff 

devices can be wired to a controller to shut off the system when it is raining. Moisture 

sensors can be wired to control valves to override the call for water if they “sense” that 

enough moisture is already present in the soil. Moisture sensors, therefore, “monitor” the 

irrigation schedule for over watering. Drip or bubbler irrigation can be used to irrigate 

slowly and minimize or eliminate evaporation, runoff and overspray. Finally, low precipitation spray, stream, and sprinkler heads with matching precipitation rates can 

dramatically improve efficiency. It is important to note that automatic irrigation systems, if not properly managed, can waste a lot of water. Always be mindful that YOU 

are the “brains” behind your irrigation system scheduling and YOU control the controller. 

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The Importance of Proper Irrigation Scheduling 

Plants require the most water during the summer and little or no water in the winter. After 

July, plants need less water each month, and by November, often little or no irrigation is 

required until March or April. Then, plant water needs increase each month through July. 

The chart below compares the typical month to month average percentage changes in 

your landscape’s water requirement to the July requirement. For example, the landscape’s 

water requirement in May is twice that of April but only 60% of the July requirement. 

This chart demonstrates the importance of regularly changing your irrigation schedule. 

Note that by the end of September, your landscape will need only about half of the water 

it needed in July. Since this chart is based upon the change by month in a plant’s water 

need, local precipitation will, of course, affect how much supplemental irrigation is needed. Check with your local water agency or Cooperative Extension office for specific 

monthly water requirements for your landscape. 

Typical Monthly Percentage Comparison of Landscape Water Need 

Using July as Basis 

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec 

0 0 5 30 60 90 100 90 60 30 5 0 

Other Water Saving Landscape Practices 

Besides proper irrigation system design and scheduling, water use efficiency in the landscape can also be increased through appropriate use of plant material, soil preparation, 

and proper horticultural practices (maintenance). 

Extensive use of plants suited for the climate of the region should be considered for 

your landscape. Plants should be grouped, as much as practical, according to their water 

requirements. Proper horticultural practices that include regular pruning, weeding, lawn 

aerating and dethatching, and the use of mulches and fertilizers should be followed. 

For more detailed information regarding water saving opportunities in the landscape 

contact your local water agency, irrigations supply store, or landscape professional. 

New Generation of Controllers 

A new generation of controllers, called ET based 

controllers, has recently become available that 

uses a measure of plants’ water requirement called 

“Evapotranspiration” (ET). ET is used to schedule 

watering based on historical climate for a locale and 

is a measure of the rate of a plant’s water requirement 

that involves plant transpiration and soil evaporation. Figure 1. Two examples of ET controllers 

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The ET rate is dependent on such weather factors as sun light, temperature, wind, and 

humidity, and varies throughout the day, by day, by week, etc. ET is usually measured in 

inches per day and is highest in the summer and lowest in the winter. In fact, often times 

no watering is needed in the winter because many plants are dormant and because winter 

precipitation meets or exceeds the plants’ water requirement (ET rate). Some ET controllers have the watering schedule programmed into their computer chip based upon 

historical ET data for a given region. Other ET controllers can change the water schedule 

weekly based on the past week’s weather for a region via a radio signal. 

Why is an ET based controller important in watering schedules? By scheduling watering 

based on ET rates, plants can receive the required amount of water to remain healthy 

without over or under watering since the ET controller adjusts the watering schedule 

automatically. Thus, the homeowner doesn’t have to guess what the optimum watering 

schedule might be throughout the year. Because many homeowners don’t adjust a controller’s watering schedule often enough, ET controllers have the potential to increase 

watering efficiency. 

Some of the new ET controllers also have temperature and rain sensors that further 

adjust the watering schedule when large differences from historical climate occur such 

as during unseasonably hot or cold spells. Ask your local irrigation supplier about the 

new ET based controllers. 

Sample Water Schedule 

The chart below shows a sample watering schedule. You can increase or decrease the 

amount of water applied to the landscape by changing either the number of start times per 

day, the number of minutes per day, or the number of watering days per week. Note in this 

example the watering times stay the same but the number of watering days per week 

change during the year. Also, note no watering is shown for the winter months. To determine the appropriate watering schedules for your area, contact your local water agency or 

landscape professional. Keep your schedule in your controller for easy references. 

Number of Watering Number of Watering 

Plant Sprinkler Starts Minutes Days per Week: Days per Week: 

Type Type per day per day Fall and Spring Summer 

lawn spray 2 7 2 3 

groundcover spray 2 7 .5 1 

shrubs drip 1 30 .5 1 

trees drip 2 30 0 .5 

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Sponsoring Agencies

California Department of Water Resources 

California Landscape Contractor Association 

California Urban Water Conservation Council 

City of Austin, Texas 

City of Santa Barbara 

Contra Costa Water District 

East Bay Municipal Utility District 

Irrigation Association 

Johnson County Water District #1 

Massachusetts Water Resource Authority 

New Mexico Office of the State Engineer 

Santa Clara Valley Water District 

Southern Nevada Water Authority 

Tacoma Water, Washington 

United States Bureau of Reclamation 

United States Environmental Protection Agency 

July 2003 

United States Environmental Protection Agency 

Office of Water (4204M) 

www.epa.gov/owm/water-efficiency/index.htm 

EPA 832-K-03-001