Irrigation Conrollers for the Homeowner
Recommended Water Saving Features
This is a cooperative effort sponsored by members of both the water and the landscape industry to promote efficient landscape water use. The purpose of this is to highlight important irrigation controller features that allow for proper irrigation scheduling. Since many people are somewhat mystified or intimidated by these devices, hopefully this 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 program it properly. 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.
Importance of Irrigation Controllers
A large part of our household water use goes to watering our landscape and many households rely on automatic irrigation systems to accomplish this. One of the most important components of an automatic irrigation system is the irrigation controller (also called the timer or clock). The controller turns the 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.
How Does a Controller Work
An automatic 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 aviod 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's 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).
Important Water Saving Features
The recommended minimum hardware for a controller when water efficiency is a priority include:
Three independent programs
Station run times from one 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, adjusting 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 occured
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 timesdetermine the upper and the 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 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 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 memoryretains 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 a 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 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.
In addition to the above hardware, programming instructions, 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 value 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 wet the soil to break the soil surface tension, to reduce runoff, or for multiple, short watering of a given area.
Ask about the warranty on any controller you are considering. The length of a product warranty is often linked to the 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 recommended features, there are other, there are other irrigation components that should be used with irrigation systems to save additional water. Control valvescontrol the flow of water to different parts of the landscape and are used for 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 devicescan be wired to a controller to shut 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, 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.
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 to 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. Not 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 a 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
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 before you 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.
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 stays 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 of landscape professional. Keep your schedule in your controller for easy references.
Plant Type Sprinkler Starts Minutes Per Day Numbers of Watering Days per Week Type 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
California Department of Water Resources
California Landscape Contractor Association
California Urban Water Conservation Council
City of Austin, Texas
City of Santa Barbara
East Bay Municipal Utility District
Johnson County Water District #1
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 Enviromental Protection Agency