Make Every Drop Count
Save time, money, and water. Follow our seven simple steps for auditing your sprinklers.
|Bureau of Reclamation/Lower Colorado Region
A third of all the residential water used in the United States—seven billion gallons a day—is spent on quenching landscaping. Half of that, estimates the Environmental Protection Agency, is lost to evaporation, wind, runoff, and ineffective sprinkler systems.
Below are our step-by-step instructions for an irrigation audit—a simple method for assessing how well your lawn’s watering system is working. “An irrigation audit is the first step in any kind of water conservation on your lawn. If you don’t know how efficient or inefficient your system is, any following measure can be useless,” says Bernd Leinauer, a turfgrass specialist at New Mexico State University. We asked Leinauer and Dan Smeal, an irrigation expert at NMSU’s extension service, to advise us on the best methods for home irrigation auditing.
What you’ll need
- 5 to 10 rigid containers, like empty soup cans or plastic cups
- paper and pencil
- half an hour of free time
Part I: Assessing your sprinkler system (the irrigation audit)
Step 1. Test for leaks
No matter what kind of sprinkler system you have, you’ll want to make sure it’s in working condition before you adjust it. Turn on your sprinklers and look for leaks, broken or eroded parts, uneven watering—sometimes patches right next to a sprinkler head get too much or too little water—and overspray onto pavement. If everything looks good, proceed to Step 2. (If you do have leaks, replace any faulty parts before moving on to the next step.)
|South Florida Water Management District
Step 2. Divide your lawn
Separate your yard into zones—designating each portion to be managed by one valve that you can turn on separately from the others. It could have just one sprinkler head, or several.
Step 3. Starting with the first zone, arrange several empty cans (or other containers) in a grid pattern.
|South Florida Water Management District
It’s important to have several cans around the zone to get an accurate idea of how much water is falling on your lawn—but also to determine whether the water from your sprinkler system is being distributed evenly. Note any big discrepancies in the measurements you take in Step 5—such as a half-inch of water in one can and an inch in another. You’ll want to adjust your sprinkler head locations or nozzles to ensure uniform watering.
Step 4. Turn on the sprinkler system for a specified amount of time (10 or 15 minutes should be enough) and let the cans fill with water.
Step 5. When the time is up, turn off the sprinklers. With a ruler, measure the depth of the water in each can and record it. Again, be on the lookout for any major differences in depth.
Step 6. If all depths are similar, calculate the average amount of water falling in the zone by first adding all the depths together and then dividing by the number of cans.
Step 7. Repeat Steps 3 to 6 for each zone on your lawn.
Part II: Assessing your needs
Knowing how much water your lawn gets is, unfortunately, only half the battle. It’s also crucial to know how much water your lawn needs, and that depends on three factors: grass, soil, and climate.
Americans use two main types of grasses on their lawns: warm season (like Bermuda grass) and cool season (Kentucky bluegrass or fescue). Ask your local nursery or landscaper if you don’t know which one you have. The Turfgrass Resource Center also provides useful guidelines for watering different types of grasses.
Soils are divided into three categories: clay, silt, and sand; loam is a combination of the three. Soils with more clay hold water longer than sandy soil, which absorbs water faster but also drains faster. Loams are somewhere in the middle. You can do a quick field test of your soil type by rolling a small ball of soil in your hand. Clay soils will stick together like a good snowball; loams will form a partial ball, and sands will fall apart. In general, clays need water less frequently than sands.
Climate and microclimate
The average rainfall and temperature in your area also affect how much water your lawn needs. The National Weather Service or a regional climate center will have regional climate information. Also, keep in mind that your sprinkler schedule may need to change in the spring and fall, since most lawns need more water at the height of summer.
Microclimate matters, too. Direct sun and wind exposure are two factors that increase evaporation rates, so look at your lawn: Is there a shady patch next to the house where the evaporation rate is probably lower? You can probably reduce the amount of watering in that area. Conversely, a patch of exposed grass may need a bit more water.
Get to It
Once you know your lawn’s needs and your sprinkler’s output, set up a watering schedule that fits your lawn, based on the needs dictated by your soil, grass, and climate analysis.
Note: If all this seems daunting, don’t fret. The Irrigation Association offers a state-by-state listing of Certified Landscape Irrigation Auditors who can do the work for you. There’s also a simpler version of the irrigation audit on HGTV.
Other things you can do
1) Water when it makes sense.
That means: not when it’s raining, and not at noon, when evaporation rates peak. Schedule watering in the early morning, or wait until the late afternoon.
2) Settle for less.
If you’re willing to sacrifice appearances for conservation, consider letting your grass turn a little yellow. “In my experience a lot of the water issues [would be resolved] if homeowners would just accept a lower quality,” says Leinauer. “Many grasses can sustain periods of drought in the summer and will come back. Bright green is not necessary year-round.”
| South Florida Water Management District
3) Choose the right sprinkler.
Most lawns use either a spray—the kind that spurts a fine, uniform mist—or rotor sprinkler, the spinning kind that kids love. Since spray systems break water down into smaller particles, Smeal says, losses to evaporation and wind may be higher. A third option is drip irrigation, a system that delivers water through underground tubing and, though more expensive and perhaps better suited to individual plants, can greatly reduce losses to evaporation and runoff.
|U.S. Bureau of Reclamation/Lower Colorado Region
4) Choose the right grass . . . or do something completely different.
It’s good to pick a grass that’s suited to your environment and climate—but it’s even better to go all-out and replace your lawn with native plants that can survive on whatever precipitation normally falls in your area. According to Smeal, xericulture, which involves planting species that require little supplemental water, is gaining traction—especially in cities like Las Vegas, which offers residents $1.50 for every square foot of lawn they replace with plants that need less water. Now, if only we could do the same thing with SUVs . . .
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