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How Long You Can Expect To Run Your Sprinklers For An Inch Of Water
By RON BAKER
Although lawn watering advice is usually offered in inches per week, there aren’t many precise ways to measure the amount of water your sprinkler system puts out.
Flow rate, water pressure, sprinkler styles, and their patterns or overlaps contribute to imprecise estimates, making it challenging for homeowners to get an accurate measurement.
Two methods can help get an accurate estimate. One option is to measure the output of each sprinkler head and then add them together.
A better option is a velocity-area method that uses flow measurements, like your home's water meter readings, to determine how much water your home’s system uses per hour.
Multiply the gallons of water your system uses in a minute by 60 to get the water output per hour. Then, divide your lawn area (in square feet) by 43,681 (square footage of an acre).
Finally, divide your water output per hour by the portion of an acre you're watering. That's how many hours of watering it will take to deliver an inch of water to your irrigated area.