Irrigation 101

In a typical residential home, water flows through various size pipes from the street through a water meter and onto your property.  The components of the irrigation system are discussed below.  If you are considering operating and maintaining an irrigation system yourself, it is highly advisable to become familiar with the various parts of that system.

Water Service

The drawing below shows how your water gets from the water main in the street to your house connection.  In a well-designed irrigation system, there is also a shut-off valve to the irrigation system.

Typical Residential Water Service

Water Meter

The water meter measures the quantity of water flowing through the pipe.  If you want to learn more about the City of Fresno Water Meter Program, visit the website at:

If you are on a water meter and not a City of Fresno water customer contact your water purveyor to learn how to read your water meter.

Note: to convert cubic feet to gallons of water multiply time 7.48 (one cubic foot of water equals 7.48 gallons).

Main Line

The pipe that comes from the water meter to the house is the main water line  which supplies all your residential water.  It should have a gate or ball valve (shut-off) where the water pipe enters the house so the water can be turned off in case of emergency or repairs.

Irrigation Main Line

An irrigation main line is a pipe that branches from the house main line in order to supply water throughout the irrigation system. This part of the system is under constant pressure.

Irrigation Shut-off

There should be an irrigation shut-off valve located closest to a water source.  The most commonly used valves are "gate or ball valves".   Typically it is near a hose connection.  It must be inserted between the connection of the irrigation main line and the domestic main water line. This allows for the irrigation system to be turned off without an interruption of water to the house. It is commonly used to isolate and stop the flow of water to one or more sections of an irrigation system during installation, maintenance, or while repairs are performed.

Backflow Preventer

A backflow preventer is a device that stops water from flowing backwards from the irrigation system and back into the house, or domestic, water supply line.

Most commonly used in home garden situations is an anti-siphon valve, which incorporates a backflow preventer into the valve.  Each anti-siphon valve must be installed 6 inches above the highest emission devices (sprinkler, drip emitter, etc.) on each valve. A special backflow prevention device is required by code if the anti-siphon cannot be installed 6 inches above the highest emission device. Check with your local building department for any additional local requirements.

Manual Valve

A manual valve is a device, operated by hand, that controls the flow of water through a pipe to the irrigation system.

Electric or Control Valve

An electric valve automatically opens when it receives an electric current through wires connected to the irrigation controller.  The valve closes when the current is stopped. Electric valves stop or open the flow of water from the pressurized pipe (irrigation main line) to the non-pressurized pipes (lateral lines) of an irrigation system. Each valve allows water into an irrigation line when opened. Electric valves require 24volt ac.

Anatomy of a Drip Irrigation System

This is a diagram of how a drip irrigation system can be installed for a home. There are several ways to combine essential components.

The above graphic and information contained in this factsheet

is partially adapted from Drip Irrigation Design Guidelines.

Jess Stryker.



A filter prevents debris from entering an irrigation system. Always use filters on drip irrigation systems. Most filters are sold separately. Some manufacturers sell units that consist of a valve, pressure regulator, and filter in one.

Pressure Regulator

A pressure regulator is a device that reduces the pressure of water from a high value to a lower value and, thereafter, maintains a constant output to a system or line. Emission devices (sprinklers, drip emitters) operate best at different levels of water pressure. A pressure regulator on the entire system, or individual pressure reducing valves, may be needed to keep emission devices within an optimal operating range.

Controller (Timer, Clock)

A controller is a device that is programmed to send electrical currents to automatic valves in order to turn it on at a pre-set time on pre-set days for a specific length of time. Controllers may be mounted on an inside wall of a garage or outside near the irrigation valves if they are designed for outdoor use. A controller that has multiple programs (A, B, C,) and multiple start times that allows the user to select particular day of the week to irrigate is recommended. With multiple programs, irrigation valves can be individually scheduled (programmed) to meet the needs of specific water-use plant types.

Types of Controllers:

Traditional Controller:  Operates automatic irrigation systems (sprinklers, rotors, drip systems).  It is recommended to select a controllers that can be set for frequency of irrigation (e.g., selected days of the week or interval watering), the start time and the duration of watering.  Some have multiple programs to allow different watering frequencies for different types of plants.  If your municipality has a watering schedule, you should select a controller that can be set to that schedule.

Smart Controller:  There are two basic types of Smart Controllers ET weather based or soil moisture.  In an ET controller, it adjusts the amount of water applied based on the evapotranspiration rate of the plant material.  The Evapotranspiration rate is with in real time with a weather station or based on historic weather averages.  Based on the information data of the area being irrigated, the controller automatically waters when needed for the length of time needed for the plants to be healthy.  The Soil Moisture controllers use a moisture sensor bar underground to detect the level of moisture in the soil at the plants roots.  It adjusts a watering schedule based on the amount of water detected by the sensor bar. Smart controllers reduce outdoor water use by an average of 15- to 30%.  They have the ability to adjust the watering times as the weather gets cooler or warmer, and they can turn off sprinklers during rain, high wind or low temperature.

Controller Terminology:

Multiple Independent Programs

An irrigation program allows for the setting of specific watering days. Having more than one program allows various valves to be set for different days. Ideally, a program will be capable of weekly (7 day) and interval programming. Weekly programming involves setting the watering days on certain named days of the week, such as every Sunday, Wednesday, and/or Friday. Weekly programming is primarily used for lawn irrigation. Check with your city for watering restrictions

Interval programming is a set number of days between irrigations. A controller that allows intervals of up to once every 30 days is preferable.    

Multiple Start Times

Smart controllers do not require setting multiple start times. If you are working with a traditional controller (not a smart-controller) it is best to set multiple start times to avoid run-off. Multiple start times allow the system to water more than once a day. For example, a controller with multiple start times can water the lawn for 5 minutes, turn off for 60 minutes, and turn on again to water an additional 5 minutes. Cycle watering allows the first irrigation water to soak into the soil (with little to no run off) before applying the second application. Clay or loamy soil and sites with slopes need multiple cycles.

Variable Run Times

The variable run time feature is not applicable to smart controllers. If you are working with a traditional controller (not a smart-controller) the variable run time feature allows for more precise watering (e.g. single digit minutes per station instead of pre-set minutes such as 5, 10, 15).

Water Budgeting

Many controllers have a water budget feature (seasonal percentage adjust feature) that will reduce the need to make manual adjustments to every station on your controller seasonally.  The water budget feature is normally just one simple click of a button to adjust the water applied to all irrigation stations.  Seasonally, change the budget to adjust for the increase or decrease in temperatures to save water.  It is always good to keep an eye on your plants to make sure the controller made a sufficient adjustment. If your plants look over watered or under watered, use the water budget feature to modify irrigation output.

Battery back-up

Battery back-up will retain the set program and internal clock in the timer in the event of a power failure.   Batteries should be changed annually.  Refer to the owners manual or an in-line site for the location and type of the battery.

Non-volatile Memory

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

Rain or Frost Sensors Device Capability

This feature allows for installation of a device to automatically override the controller settings in the event of rain or heavy fog.  These devices turn off the power to an automated irrigation system during rain or heavy fog.  When the senor dries out it allows the programming to continue.

Frost sensors turn the power off to automated valves when the sensors detect low temperature or frost.  After frost has past, it allows the valves to operate as programmed through the controller.

Using Your Irrigation Controllers Seasonal Percentage Adjust or

Water Budget Feature to Help Conserve Water


Most irrigation controllers (clocks or timers) have a seasonal percentage adjust or water budget feature which allows the garden a simple way to best manage water as seasons change.  When the season percentage adjust is altered by the gardener or an automatic modular unit the controller makes changes to the amount of water (through adjusting the run time) your garden receives. Water budgeting increases or decreases valve run times based on a percentage (%) on all programs in one easy step.

July is the month when plants in the Fresno/Clovis area require the most water. The following recommended settings are based on the average evapotranspiration rate for our area.

The Procedure:

Step 1: Ensure the time and date on the irrigation controller are correct.

Step 2: Set the program start time(s) when outdoor irrigation is allowed.  To avoid run off it is recommended that more than one start time is set.  This is called cycle and soak.  Set the start times so the controller will cycle through the values/stations and rest then start again soon after.  It is suggested to use start time off the hour to prevent water surges. For example:

Start Time 1 set for 3:05 a.m.

Start Time 2 set for 4:05 a.m.

Start Time 3 set for 5:05 a.m.  

Be sure that the irrigation stops running before the end of the allowable window for irrigation.  For example, in the City of Fresno, there is no outdoor watering from 6:00 a.m. until 7:00 p.m., so all the irrigation valves would be finished running before 6:00 a.m.  

Step 3: Set each zone/station run time based on the number of start times you selected. For example:

Let us use July with a cool season grass irrigated by spray heads as our example.  We chose to water three days a week, and cycle three times on our watering days to avoid run-off; then 63 minutes per week divided into 3 days equals 21 minutes per day.  Three cycles per day makes the 21 minutes per day into 7-minute cycles.

Step 4:  Ideally, timers should be reprogrammed monthly.  If your irrigation timer has the water budget (%) feature, the timer may be programmed in the spring for the anticipated July usage (100%) and then adjusted on a regular basis to reflect the monthly % of July, rather than reprogramming all of the run times.  Using the example above with the lawn needing 63 minutes a week in July, by setting the Water Budget (%) for March at 40%, roughly 25 minutes of irrigation will be applied (63 minutes x 40% ), divided equally between the days of the week and all cycles.  If your controller budgeting is in increments of 10%, round up to the next higher percent. If you feel the lawn is not receiving enough water, increase the water budget percentage. If you feel the lawn could do as well with less water, reduce the water budget percentage.

The following chart shows the approximate lawn watering time needed in minutes per week for both warm and cool season grasses using both spray and rotor heads if there is no rainfall.  Warm season grasses grown in our region include Common Bermuda, Hybrid Bermuda, Saint Augustine, Zoysia, and Buffalograss. They thrive in warm weather and turn brown due to dormancy in cold weather.  Cool season grasses grown in our region include both Fine and Tall Fescues and Perennial Ryegrass (used to over seed winter-dormant grasses); these grasses thrive in the spring and fall and maintain their color year round.  Cool season grasses require approximately 40% more water than warm season grasses.

To use this chart, remember that the minutes of watering time needed is for an entire week, so you must consider the frequency that you are going to water during the week.

Approximate Lawn Watering time (minutes per week)

Warm Season Grass             - - -                Cool Season Grass



% of





% of
























































































The percentages given above are based on historical averages and may not meet the current needs of your lawn due to unusual weather.

[Adapted from an article prepared by Curtis Swift, Ph.D., Colorado State University Extension, Tri River Area]