Watering Your Lawn

The amount of water your lawn needs depends on a variety of factors, including type of turf, how fast the soil absorbs water and how much water pressure your sprinkler system releases.

For small and average-sized yards, the differences may not amount to much. If you have a typical system, use the chart below as a guideline.

Watering

Recommended watering minutes per zone (for lawn, based on three days per week)

• Set your irrigation clock to water only what each zone needs. See the run-time scheduler for precise watering times for each type of landscape.
• Program your system to water in cycles – five minutes on, five minutes off – to allow water to soak into the ground.
• Be sure your rain sensor is working correctly, and replace it if it's not.
• Check irrigation heads after mowing to be sure they are not damaged.
• Realign any heads that are spraying too high in the air, across pavement or into tall grass.
• Check for system leaks and repair them as soon as possible to avoid wasting water and damaging foundations or landscape features.
• Consider installing soaker hoses, sub-surface piping or drip irrigation for your flower beds and shrubs.

More than 50 percent of an average household’s annual water consumption is from watering outside. Auditing your sprinkler system, and fine-tuning its performance, can help save water. Thoroughly check your system each spring when you first turn it on. After each mowing, check to make sure sprinkler heads haven’t been broken or knocked out of alignment.

Create a better sprinkler schedule with a checklist to help you understand all areas of your yard. Write down the number of minutes you water per zone. If your clock has more than one program, fill out a separate checklist for each program. Each program has separate start times.

• Inventory your sprinkler system
  Turn on one zone at a time and collect the information requested on the checklist. Use the completed checklist to develop a watering schedule with the run-time scheduler. Once a week after mowing, go through the zones to make sure everything is functioning properly.
• Watering a slope
  If you have a watering zone on a slope, water in five-minute cycles to prevent runoff. Use the run-time scheduler to develop an efficient schedule.
• Improve maintenance
  Some of the other information you collect on the checklist will help with general maintenance of your sprinkler system. Dry spots indicate areas where the sprinkler heads need to be adjusted. Wet areas could be caused from a leak in the system or low-head drainage. If you notice a leak, fix it as soon as possible to avoid water waste and other problems.

Use the catch-can test to make sure your lawn is using only what it needs.

• Set four identical cans at various distances from the sprinklers within the spray pattern of the sprinkler zone. Write down the location of each can and turn on the sprinkler zone for 15 minutes.
• After 15 minutes, turn off the zone and measure the water level in each can with a ruler. Write down the amount of water inside each can. Differences in the amount of water in each can will tell you what areas within each zone need more or less water.
• Move or adjust the sprinkler nozzle to make each zone more efficient.
• Pour all the water into one can, which equals the amount of water your sprinkler system delivers in one hour.
• Based on this number (inches per hour), you can determine how long the sprinkler must run to provide your lawn with the amount of water it needs. For example, in June, a typical Kentucky bluegrass lawn needs about 1.5 inches of water a week, which means you should water your lawn about a half inch three times a week. Smaller watering cycles are better than large, so do not water your lawn the full weekly amount in one day. Follow these guidelines:

• May – 1.2 inches per week
• June – 1.5 inches per week
• July – 1.5 inches per week
• Aug – 1.2 inches per week
• Sept. – 1 inch per week
• Oct. – .67 inch per week

There are three types of hose-end sprinkler attachments, two that move and one that doesn’t.

• Oscillating sprinklers roll back and forth and spray vertically, which may lose a lot of water to evaporation.
• Impact sprinklers spin slowly around or from side to side and apply water at a slower rate than oscillating sprinklers. They lose less to evaporation.
• Pop-up sprinklers move only up and down while applying water. They can irrigate faster than some soils can handle, regardless of the spray pattern. These sprinklers should be re-positioned and re-aimed often to avoid wasting water.

With manual watering methods, use the watering-times table to determine the approximate output of your sprinkler. Set a timer each time you direct the sprinkler to a new part of your yard.

There are two basic types of sprinkler heads, pop-ups and rotors.

• Pop-up spray heads deliver 1.5 to 2 inches of water per hour in a fan-shaped spray, or sometimes in a full-circle spray.
• Rotor spray heads deliver about a half inch of water per hour in a rotating jet of water.

Pop-up systems that spray a steady fan of water can water four times as fast as rotor systems. Most soils in Denver can absorb about a half inch of water per hour. If the soil is getting too much water too fast, water will run off and be wasted.

• Add a weather-based smart controller to your irrigation system to save water. Weather-based smart controllers, sometimes called ET or evapotranspiration controllers, take into account air temperature, relative humidity, solar radiation, wind and natural rainfall to regulate the amount of water applied to your lawn. Denver Water offers rebates for certain weather-based smart controllers.
• Rain sensors stop your sprinkler system from coming on in the rain. Denver Water offers rebates for certain models of rain sensors.