Choosing an Irrigation Control System

~ Manual systems keep you in touch with your garden and it’s water needs. You must decide each day if, when and how much to water. You must be there when it’s time to turn the system on and when it’s time to turn it off. Studies show that people with manual systems use less water than people with automatic systems.

~ Semi-Automatic systems, which work similar to a kitchen timer, require you to turn the water on manually but the system turns itself off at the end of the time (or number of gallons) you set.

~ Automatic systems are the most common type. They use an electronic controller to do all the work for you. Traditional automatic systems never forget to water . . . even if it’s raining. Because we can ignore automatic systems, studies show that people with these systems use more water than people with manual systems.

~ Smart systems, which are now affordable for residential use, add sensors and/or telemetry to the controller to adjust automatically for the day-to-day weather changes in your garden. Studies show that Smart controllers save a lot of water.

How Much / How Often - Check with your city or water agency for water restrictions

You have three choices to make about your watering schedule:

1. What time of day to water [If you have an automatic controller, this is usually called Start Time or Cycle Start]

In general, to reduce water loss by evaporation, it is best to water during the early morning hours if you are using a spray system. For drip systems, you may choose any time you like. Sometimes, when using watering devices, like sprayheads or bubblers, which apply water faster than the soil can accept it; you may need several start times spaced out over a longer period. See Too Much, Too Fast? below.

2. How long to water [Run Time or Water Time]

This is the hardest one to figure out. It is the time that it takes to refill the soil reservoir in the root ball of the plants and is a function of the type of plant, its root depth, the type of soil and the current weather. It is possible to mathematically calculate this number but someone has already done that for you. Go to the MWD website at http://www.bewaterwise.com and use the Watering Calculator to establish a beginning controller program for your garden or check out the Watering Tips.

After living with this program a while you may want to adjust it, but this will put you in the ballpark and assure that you are not overwatering. (If you have a native plant garden, overwatering is about the only thing that can kill your plants.) Ordinarily, once you've figured out how long to water, that number should only be changed to adjust for root growth.

If you are using a watering device that has a high application rate or the planting area is on a slope or you have clay soil that can’t absorb the water fast enough, it may be advantageous to divide this time up into several shorter applications to avoid run-off. See Too Much, Too Fast? below.

3. How often to water [Day Interval or Skip-A-Day]

(The MWD Watering Calculator will figure this out for you too or use the Watering Tips.)

Unless you have a Smart controller to do the work for you, increasing or decreasing the frequency of watering should be your primary method of seasonal adjustment. The number of Days Between Waterings is the best way to think of this. Unless you have a specific need to avoid watering on certain days of the week, you will find this the easiest way to make seasonal adjustments. Some controllers allow frequency to be scheduled only by days of the week. These settings are referred to as Day Settings, Days of the Week or Days On.

Smart , WBIC or ET Controller

What is a “smart” irrigation controller?

“Irrigation controller” is a term that landscape professionals often use when referring to the device (typically a “timer”) that controls your home’s outdoor sprinkler system. However, unlike timers, which water on a set schedule, “smart” irrigation controllers use regional weather, site, or soil moisture data as a basis for determining an appropriate watering schedule.

Also known as “WBIC,” “weather-based,”  “ET- or Evapotranspiration-based,” or “soil moisture sensor-based” controllers, “smart” irrigation controllers have an extensive history of scientific and field documentation. Golf courses, parks, and athletic departments have used climate-based irrigation systems for more than 20 years. This scheduling technology is available for smaller landscapes through “smart” controllers.

How do smart irrigation controllers work?

Traditional irrigation system controllers are really just timers. They turn the water on and off based on a pre-programmed schedule, regardless of the actual weather conditions. Smart irrigation controllers, on the other hand, monitor and use information about environmental conditions for a specific location and landscape, information such as soil moisture, rain, wind, evaporation rates, plant transpiration rates, and more, to determine when to water and when not to in order to provide the right amount of water to maintain healthy growing conditions.

Because “smart” irrigation controllers are more efficient than traditional, timer-based controllers, they maximize water use efficiency, often reducing usage by 15 percent or more, which saves you money and makes large, positive impacts on your community’s efforts to assure the local water supply.

Smart Controllers self adjust watering schedules according to wind, rain, solar radiation, and humidity. They have the capacity to operate multiple programs and to irrigate during desired times and/or dates.  Smart controllers use one of the following technologies to self adjust watering schedules:  1) onsite weather sensors; or 2) satellite reads from local weather stations; 3) historical weather data pre-programmed into the controller.

These controllers can reduce run-off, lower your water bills and make your plant material look more resilient, if you have an efficient irrigation design and adequate hydrozones. Smart controllers are not a hands off solution; it is advised that you monitor your plant’s health. For more information on smart controllers visit the Irrigation Association’s Web Site at: http://www.irrigation.org/smartwater/ .

How does a smart controller make watering my landscape easier and more convenient?

Traditional sprinkler timers require manual adjustments every time the weather changes. “Smart” controllers automatically adjust the watering schedule based on local weather/site conditions. Once the initial setup and monitoring is complete, there’s no need to reset the timer unless your plants show stress.

How will installing a smart controller save me money?

A smart controller saves you money by reducing your water use. Your actual water savings will depend on how you have watered in the past. Pilot studies have shown typical water savings to be in the range of 15 - 20 percent annually. Smart controllers also save money by providing a healthier landscape, since a landscape which is properly watered will be less likely to suffer from fungal disease and insect infestations that can require costly treatments, thereby protecting your landscape investment.

Where can I purchase a smart controller?

Smart controllers are generally only available through irrigation or landscape contractors.

Can I install a smart controller myself?

The proper installation and initial setup of smart irrigation controllers generally require an in-depth knowledge of soils, precipitation rates, slope measurements, and related factors. Therefore, we strongly recommend you work with a certified irrigation contractor who is experienced in the installation of smart controllers.

What questions should I ask before purchasing a smart controller?

The Irrigation Association, a non-profit organization supporting water conservation through efficient irrigation, has published an Irrigation Consumer Bill of Rights (http://www.irrigation.org/pdf/bill_rights-turf.pdf) to educate consumers about the questions to ask their contractor before purchasing a new irrigation system. Be sure to read it prior to meeting with your landscape professional, and before beginning any work, and confirm that your contractor is specifically trained in the installation of the smart controller selected.

Where do the automatic adjustments come from?

Smart controllers receive the environmental data they need from various sources, depending on the make and model. Some models use data from local weather stations or on-site sensors, while other models gather information from several weather stations linked to match the zip code and address of the installation site. Each type has the capability to work equally well. Look for the type suited to the unique attributes of your home landscape.

How much do smart controllers cost?

The cost of smart controllers varies according to the number of zones and features included in the controller model you select. Most range in price from a few hundred dollars on up, plus installation. In addition, some weather station-adjusted controllers require a small monthly or annual fee for transmission of daily weather information. Other, internal sensor-based smart controllers rarely require transmission fees.

Which smart controller works best?

Different smart controllers each have different features and benefits. A certified landscape/irrigation contractor can help you make the best choice for your specific needs.

How have these products been tested?

Manufacturers of smart controllers rigorously test their products before releasing them for sale. In addition, the Irrigation Association has recently developed an independent third party testing protocol specific to smart controllers. The results of these tests are available at http://www.irrigation.org/gov/default.aspx?pg=swat_perf-reports.htm&id=214.

If I install a smart controller, will I get a discount on my water bill?

Less water used for sprinkling means less water delivered through your water meter. When you reduce water use by installing a smart controller, your reduced use will result in a reduced water bill.