IRRIGATION CONTROLLERS
FOR THE HOMEOWNER AND GROWERS.
Recommended Water Saving Features
Water—too precious to waste!
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 a timer or clock).
The controller turns the irrigation system on and off at
the times you select. In other words, the irrigation 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 irrigation
controller, properly scheduled, can result in significant
water savings and lower water bills.
How Does a Irrigatin Controller Work?
An automatic irrigation controller 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 irrigation 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).
Important Water Saving Features
The recommended minimum hardware features for a
controller when water efficiency is a priority include:
Hardware Features
• Three independent programs
• Station run times from one to 200 minutes
2
• 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 irrigation 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
Other Important Components of an Efficient Irrigation System
Besides obtaining an irrigation controller with the recommended
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.
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.
