Many homeowners have irrigation systems to water their lawns. Irrigating lawns can help maintain a healthy sod during the heat of the summer, but when to water the grass and how much to water the grass are questions that deserve deeper investigation.
The United States Environmental Protection Agency (EPA) estimates the average American family uses about 320 gallons of water per day, of which, about 30% is used outdoors, including irrigating lawns and gardens. Given a ballpark US population of 333 million folks, and an average family unit size of 3.13 people, that’s a little over 106 million families, meaning our lawn and garden irrigation usage across the country equals about 10 billion gallons of water per day (repeating for emphasis, to water the lawn and garden). Can these estimates be true? Is it really possible we use the equivalent of 15,150 olympic sized swimming pools of water everyday (on average) to keep our grass green?
I offer facts to make a case. I lived in a New Kent County subdivision for several years and kept track of my water usage from October 1, 2005 through September 30, 2008. During that time, my family’s annual domestic (inside) water consumption averaged 48,400 gallons. Over the same period, our irrigation usage more than doubled, at 100,500 gallons per year. New Kent County Director of Public Utilities says, “one thing people don’t understand is we have to build pumps, tanks, wells, etc., to meet the peak demand, not the average demand, and thus much of that infrastructure is oversized most of the year.”, noting that county-wide peak demand in the summer is approximately 100% more than the winter demand, due mostly to irrigation usage.
So, is it really necessary to water the lawn in eastern Virginia? For certain, it does get hot here in the summer, however, traditionally, most of our rainfall comes in June, July, August, and September. Virginia Cooperative Extension Publication 430-010, Summer Lawn Management: Watering the Lawn, notes that most turfgrasses require approximately one inch of water per week (rain or irrigation) to sustain growth during warmer conditions, although specific site conditions such as type of grass, soil conditions, etc., may dictate adjustments. Lower amounts of water, especially during very hot periods, may cause turf to go dormant. Dormant lawns will lose their deep green color and may turn pale or even brown. A dormant lawn will recover when water is applied again. If conditions are extreme, the lawn may die and require replanting when the time is right.
Overwatering brings its own set of pitfalls. Too much water can lead to excessive vegetative growth, requiring more frequent mowing, and can lead to outbreaks of fungal diseases such as brown patch and gray leaf spot. If you choose to irrigate your lawn, set your system to run around dawn, water deeply and infrequently, and adjust your sprinkler heads to avoid irrigating the driveway, sidewalk, and street.
Remember the purpose of your lawn is to stabilize the soil around your home to prevent erosion… croquet with the Queen is an unrealistic goal.
“Outdoor Water Use in the United States.” United States Environmental Protection Agency, https://19january2017snapshot.epa.gov/www3/watersense/pubs/outdoor.html. Accessed 29 April 2024
“Summer Lawn Management: Watering the Lawn” Publication 430-010, Virginia Cooperative Extension, https://www.pubs.ext.vt.edu/content/dam/pubs_ext_vt_edu/430/430-010/430-010.pdf. Accessed 29 April 2024
McCall, David. “Lawn Diseases” in Homes, Lawns, and Animals, 2024 Pest Management Guide, Publication 456-018, Virginia Cooperative Extension.
https://vtechworks.lib.vt.edu/server/api/core/bitstreams/e0666e93-8cae-481f-b8f2-64eb588b6370/content. Accessed 29 April 2024
For more detailed and site-specific information, please consider participating in the Turf Love program offered through the Colonial Soil and Water Conservation District.
Read more articles in the Summer 2024 CSWCD Newsletter.
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