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Watering Your Lawn

Lawns, especially on large properties, can consume a lot of water. But by making sure your sprinkler system is running efficiently, and only giving your lawn what it needs, you can have a green, healthy lawn while cutting down on your water consumption. Take the time to learn about your sprinkler system, your lawn and your water usage to irrigate efficiently.

There are no assigned watering days, but watering two days a week should be sufficient during most of the summer. If needed, water a third day only during extreme heat or dry periods. Customers are subject to annual watering rules.

How to cycle and soak your lawn

One of the best ways to use water efficiently on your yard is to cycle and soak. Watering in increments gives soil time to soak up the necessary water and allow water to travel further into the soil where the grass roots are, creating a healthier lawn.

Using the scheduling features on an irrigation controller, add multiple start times and reduce each zone’s watering time. Allow for up to an hour between start times to allow for the last cycle of irrigation to soak into the soil. Water, rest, water.

For example, a 14-minute run time may be irrigated for 7 minutes, turned off while the controller advances to irrigate another zone, then irrigated for the remaining 7 minutes to achieve the total 14-minute run time.

Learn more about the cycle-and-soak method from the Colorado State University Extension.

The simplest way to regulate lawn watering

The chart below is a starting point for the number of minutes to water each sprinkler zone on the days you determine watering is needed. These times are averages. Adjust your watering minutes based on rainfall, type of grass or plants, sunny or shady locations and other characteristics.

Watering two days a week should be sufficient during most of the summer. If needed, water a third day during extreme heat or dry periods. Water trees and shrubs as needed, but not between 10 a.m. and 6 p.m. Shrubs and perennials need half as much water as lawns.

There are no assigned watering days, but never water a zone more than three days per week.

Minutes to water per zone
(For bluegrass, based on sprinkler type.)

Fixed spray head
Fixed spray heads

Rotor head
Rotor heads

Rotary/high-efficiency nozzle
Rotary/high-efficiency nozzles*

Manual sprinkler
Manual sprinklers

January – April Water trees and shrubs as needed.
May 12 24 30 18
June 17 35 43 26
July 18 36 45 27
August 14 27 34 20
September 11 23 28 17
October – December Water trees and shrubs as needed.

These times are based on a sprinkler system running at an efficient level. Watering is not allowed between 10 a.m. and 6 p.m.

*Rotary//high-efficiency nozzle information.

Other irrigation tips

  • Set your irrigation clock to water only what each zone needs.
  • Looking for an easy way to see if your lawn needs water? Probe your lawn with a screwdriver. If it goes into the soil easily, that indicates sufficient moisture. If the screwdriver can’t probe the soil, apply water to that area. Two days of watering a week should be enough; if it’s dry, add another day.
  • 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.

Audit your sprinkler system

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.

Use a checklist

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. 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.
  • 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.

Catch-can test

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

Hand watering

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.

Sprinkler systems

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.

Smart sprinkler system controller

Add a smart irrigation controller, which acts like a thermostat for your sprinkler system by telling it when to turn on and off, to save water. Denver Water offers rebates for WaterSense-labeled controllers.

  • During irrigation season, be aware that smart irrigation controllers must not operate between 10 a.m. and 6 p.m. In rare conditions, the controllers may operate more than three days a week.