Irrigation
for Your Home Landscape
(Best Management Practices)
 

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Here are some ways Denver Water customers can use water wisely for landscape irrigation whether you drag hoses for manual sprinkling or rely on an automated irrigation system. These practices for managing water use are divided into three groups: Manual Applications, Irrigation Systems, and General Tips that apply to both. Near the end of the page you will find instructions for figuring out how much water your sprinklers put out. you can use this information with the chart that indicates recommended minutes of water per week for Bluegrass lawns.

Please post this list where you'll see it often and follow these Best Management Practices ("BMPs," if you like acronyms) to keep your yard healthy and green with little water waste.

Hoses and Hose-End Sprinkler
Attachments for Manual Application

There are three basic kinds of hose-end sprinkler attachments: two kinds that move and one that doesn't.

• Oscillating sprinklers, which roll back and forth, spraying vertically, may lose a lot of water to evaporation.
• Impact sprinklers, which spin slowly around or from side to side, apply water at a slower rate than oscillating sprinklers, and lose less to evaporation.
• Sprinklers that move only up and down (pop-up) while applying water can irrigate more quickly 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 instructions in the table below to determine the approximate output of your sprinkler, then set a timer each time you direct the sprinkler to a new part of your yard.

Pop-up spray head

Rotor spray head

In-Ground, Clock-Controlled
Irrigation Systems

There are two basic types of irrigation system sprinkler heads: pop-ups and rotors.

• Pop-up spray heads deliver an average of 1.5 to 2 inches of water per hour in a fan-shaped spray, or sometimes a full circle spray.
• Rotor spray heads ("impact heads") deliver an average of 0.5 inches of water per hour in a rotating jet of water.

Pop-up systems that spray a steady fan of water can provide water four times as fast as rotor systems. Most soils in the Denver Metro area can only absorb 0.5 inches of water per hour. If the application rate is more than the absorption rate, water will run off the landscape and be wasted. Specifically, running pop-up spray heads for an hour provides water too fast and increases waste. This costs you water and money!

ET Controllers/Rain Sensors:

• Add an ET Controller to your irrigation system to save even more water -- especially if you have a large lot!  By taking into account air temperature, relative humidity, solar radiation, wind and natural rainfall, an ET Controller calculates the degree of evapotranspiration and regulates the amount of water applied by your irrigation system.
• A $150 rebate is available for certain ET controller models.  Contact your irrigation or landscape service provider to help you with a purchase and installation.
• Denver Water offers a $25-$50 rebate for certain models of rain sensors

How to best manage irrigation systems:

• Set the irrigation clock to water only the needed amount on the various types of landscape in each irrigation zone. (See the Run-Time Scheduler for precise watering times for each type of landscape.)
• Use repeat cycle programming with pop-up heads to reduce runoff. Schedule each sprinkler to water for a portion of the time required, then "rest" while the water is soaking into the ground, then repeat.
• 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.
• Re-align any heads that are spraying too high in the air, across sidewalks or driveways, or into tall grass.
• Check for system leaks and repair them ASAP to avoid damage to building foundations and other landscape features. This will save you money on your water bill too.
• Consider non-spray irrigation for your flower and shrub beds. This includes soaker hoses, sub-surface piping, and drip irrigation.
• Consider installing a wind-sensor that will shut down your irrigation system when winds get too high.

Measuring Sprinkler Output

To measure the output of your sprinkler heads...

Set four identical cans at various distances from the sprinkler within its spray pattern. Turn on the sprinkler for 15 minutes. Turn off the sprinkler and pour the water collected from the four cans into just one can. With a ruler, measure the depth of water in the can. This is the amount of water your sprinkler delivers an 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. Once you know how much water your sprinklers put out, set them to water for the number of minutes necessary to apply the amount of water shown in the chart below. When using the chart, keep in mind that the number given is the total water for the week, not the amount to water on each watering day. What does this mean? For example, in June a typical Bluegrass lawn needs about 1.5 inches of water per week. To provide this, you might spread the water evenly over three watering days by applying a half inch on each watering day. But you might give each area one inch of water on your first watering day and another half-inch on the second, or even use the repeat cycle approach, giving the lawn short "bursts" of water interrupted by non-watering cycles to allow the water to soak in. In general, smaller watering cycles are better than large, so it would not be the best water management to give the lawn its entire 1.5 inches for the week on one day.

Tips for the Best Management of
Both Manual & Automatic Systems

To save water and money, apply only the amount of water your landscape needs:

• Measure the output of your sprinkler as described below, then calculate the minutes you need to water for each kind of sprinkler.
• Apply the proper amount to grass, and different amounts to shrubs, flower beds, and vegetable gardens.
• Water your landscape in the cool hours of the day: early morning or early evening when pressure is best.* Contrary to folklore, watering at night in Colorado does not cause lawn disease unless you are watering too much.
• Water only when the wind is calm.
• Count nature's contribution. If it rains, those inches of rain can be deducted from your lawn's water needs for the week.
• Be sure to water growing things only! To date, no benefits have been shown from trying to get concrete to grow!

* Denver Water has adopted a permanent restriction against watering with spray irrigation between 10 am and 6 pm from May 1 to September 1.

The Simplest Way to Regulate Lawn Watering

Many factors go into determining how long you should water your lawn each week, some of them easy to understand and measure, others very technical. How well your soil absorbs water is a critical issue, for example, and dependent on things like soil composition and percentage of organic matter. Another obvious issue is the water pressure in your irrigation system, which may vary depending on neighborhood usage, number of taps open, someone taking a shower inside the house. Finally there is the question of grass type, which can cut or increase your water needs drastically. Turf-type Tall Fescue, for example, needs only half the amount of water required to keep bluegrass healthy.

For small and average-sized yards, the differences may not amount to much. If you have a typical system, then the table below does the math for you. However, if you have a large yard, or you want to minimize your water use, it might be worth the effort to determine the actual output of your sprinklers.

Chart:

How Much Water Does a Healthy Lawn Need?

Watering Times will help you determine how long to water each zone on your watering day.

WATERING MONTHS	WATERING TIMES (minutes per zone, no more than three days a week)
	Fixed Spray Heads	Rotor Heads	Manual Sprinklers
JAN-APRIL	Water as needed, especially trees and shrubs
MAY	13	29	20
JUNE	20	43	30
JULY	23	50	35
AUGUST	20	43	30
SEPTEMBER	13	29	20
OCTOBER	Water as needed, especially trees and shrubs

Keep in mind, if you adopt this chart as your watering guideline, that the number of minutes is per watering day, and are average watering minutes. You may need much less water on your yard, or perhaps a bit more water depending on your individual yard and landscape.  If you have a typical rotor sprinkling system, you can set the clock times for 43 minutes in June, water your lawn on two or three watering days a week, and keep the lawn healthy. Remember that shorter times with higher frequency are better for the lawn. Instead of setting your timers for one 43 minute cycle on your watering days, use the repeat cycle approach, giving the lawn two waterings of 21 minutes each, spaced a half hour or so apart so the application can soak in.

To best manage your lawn's look and health, let these Best Management Practices grow into habits. Your outdoor water use will be sensible and efficient. Even when droughts return, these practices can help your landscape survive.