How to Water
The recommendations on this page could reduce the amount of water you use for irrigation by 20-30 percent.
#1 Water on Schedule
Plants come in four categories – high, moderate, low and very low water use – and the recommended watering times are different for each category. And, watering times vary by season. It’s complicated, but we have two tools that make it simple.
Use the city of San Diego’s Landscape Watering Calculator. Enter your zip code, plant category, soil type and sprinkler type and it will give you recommend watering times for each month of the year.
Weather-based, or smart, irrigation controllers automatically adjust watering times each day. They do this based on weather data, from sensors you install on your property, or from the State of California’s CIMIS weather stations accessed through the internet.
#2 Use the Most Efficient Sprinkler
Our sprinklers put a lot of water on our landscapes, but only a percentage of it is absorbed into the soil and into the roots of our grass, plants and trees. The higher the percentage, the more efficient the sprinkler is.
Spray nozzles are very common but have two issues: they apply water faster than most soils can absorb it, and wind can blow the small water drops off target — causing water to run on to sidewalks and into the street.
Rotors shoot a single stream of water that moves slowly over a landscape, giving soil time to absorb the water. Rotors are commonly used on large landscapes.
Rotary nozzles apply water slowly and produce large, wind-resistant water drops. They can be up to 30 percent more efficient than spray nozzles and are the best choice for watering a lawn.
Video: Replacing spray nozzles with rotary nozzles is simple.
Drip irrigation applies water slower and deeper into the soil, and is the best way to water plants and trees. Not irrigating the area between plants saves a lot of water and reduces weeds, and installation is easy – watch this video.
#3 Prevent Water Runoff
If your sprinklers apply water faster than your soil can absorb it, water will run off of your landscape, on to the sidewalk and into the street. You can avoid runoff by using rotary nozzles and drip irrigation, or by reducing your watering times and watering more often.
Use Multiple Start Times
Some irrigation controllers offer multiple start times on the same day within one program, while other controllers require you to use multiple programs.
On Start Time 1 or Program A:
Schedule the same days and 3:00 minutes at 12:00am
On Start Time 2 or Program B:
Schedule the same days and 3:00 minutes at 2:30am
On Start Time 3 or Program C:
Schedule the same days and 4:00 minutes at 5:00am
Use the Cycle and Soak Option
Some irrigation controllers have a cycle and soak option, which will automatically divide a 10 minute watering cycle into smaller cycles.
#4 Regulate Your Water Pressure
The optimal water pressure for drip irrigation and sprinklers ranges from 20-40 psi. But a home’s water pressure can be as high as 70 psi.
Below is an excerpt from a spray nozzle performance chart. The nozzle’s optimal water pressure is 30 psi, and at 40 psi the nozzle’s flow rate increases by 0.4 gallons per minute. That’s wasted water. It doesn’t sound like much, but it adds up quickly.
Gallons wasted by one sprinkler in 10 minutes
Gallons wasted by 60 sprinklers in 10 minutes
Gallons wasted by 60 sprinklers in one year
Measure Your Water Pressure
Water pressure gauges are available at hardware and irrigation supply stores. Screw a water pressure gauge on to a hose bib outside your home and turn the water all the way on. If your pressure is higher than your sprinklers’ optimal pressure, you’ll save water by installing pressure regulation devices in your irrigation system.
Install Pressure Regulation
Manufacturers make pressure regulators and valves and sprinklers with built-in pressure regulators. Learn more by watching videos on manufacturer websites and ask one of the experts at an irrigation supply store what they recommend.
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