Guide
How Much to Water Your Lawn: The WaterSense Way
The short answer
EPA WaterSense says most landscapes need about one inch of water a week, including rainfall, though it varies by place, weather and plants. Water early in the day rather than midday, when the sun evaporates much of it. To time your sprinklers, set out a few empty tuna cans, see how long it takes to fill them with half an inch of water, and water that long twice a week, adjusting for weather. Turn the water off if it starts to pool.
A green lawn doesn’t need as much water as most sprinklers give it. Overwatering wastes money, encourages shallow roots and weeds, and sends fertilizer down the street drain. This guide uses EPA’s WaterSense program to set a simple, adjustable watering routine. Your local water utility may have rules or watering days; check with it first.
Why it matters (EPA WaterSense): outdoor water use accounts for more than 30 percent of total household water use on average, and can be as much as 60 percent in arid regions. As much as 50 percent of the water used outdoors is lost to wind, evaporation and runoff from inefficient irrigation.
How much water does a lawn need?
WaterSense says a landscape typically needs about one inch of water a week, including rainfall, and that the amount varies with where you live, recent weather and the plants in your yard. Your local water utility or a cooperative extension office can tell you what grass types in your area need.
What time of day should you water?
Avoid watering in the middle of the day, when the hot sun evaporates much of the water before it reaches the roots. Early morning, when it is cooler and calmer, is a common choice. Skip watering after a good rain.
How do you time your sprinklers with the tuna-can test?
- Place a few empty tuna cans (or any straight-sided containers) around the lawn.
- Run the sprinkler and time how long it takes to fill the cans with half an inch of water.
- Water for that amount of time twice a week.
- Watch how the lawn responds and adjust for weather.
Different zones often fill at different rates; time each one. If the cans fill unevenly within a zone, some heads may be clogged, tilted or broken.
What if the water puddles or runs off?
If water starts to pool, turn off the sprinkler. WaterSense warns that overwatering leads to weed growth, disease, fungus and runoff that carries fertilizer and pesticides into local waterways, and that watering too often can drown plants or cause shallow roots. On clay soil or slopes, try cycle and soak: split each watering into shorter runs with breaks between so the water soaks in.
Can a smart controller help?
Yes. WaterSense labels two kinds of irrigation controllers that water based on need instead of a fixed clock: weather-based controllers and soil moisture-based controllers. WaterSense says replacing a clock-based controller with a WaterSense labeled controller can reduce an average home’s irrigation water use by up to 30 percent and save up to 15,000 gallons a year. Some utilities offer rebates; check yours.
How do you keep a sprinkler system in shape?
- Inspect it each spring for heads damaged by frost, mowers or cars.
- Look for soggy spots, geysers or water on pavement, which point to leaks or misaimed heads.
- Group plants with similar water needs in the same zone.
- Consider an irrigation professional certified by a WaterSense labeled program for an audit; WaterSense says a well-managed system can cut a household’s irrigation water use by 15 percent.
WaterSense says a leak in an irrigation system 1/32 of an inch across can waste about 6,300 gallons a month; see our leak guide for more checks.
Adding new sprinkler lines, trees or beds?
Any digging, even for sprinkler lines or a new tree, should start with a free request to 811 a few business days ahead. See our 811 guide. For trees in the lawn, see our tree care guide.
Lawn watering is part of our spring and summer home maintenance checklist.
Step by step
- Check local rules. Ask your water utility about watering days and how much your grass needs.
- Set out tuna cans. Place a few empty cans around the lawn in each sprinkler zone.
- Time half an inch. Run the sprinkler and time how long it takes to fill the cans with half an inch of water.
- Water twice a week. Water for that time twice a week, early in the day, skipping after rain.
- Stop at puddles. If water pools, turn it off and switch to shorter cycle-and-soak runs.
- Inspect each spring. Check heads and lines for damage and leaks before the season starts.
Frequently asked questions
How much should I water my lawn each week?
EPA WaterSense says landscapes typically need about one inch of water a week, including rainfall. It varies by location, weather and plants, so check with your local water utility.
What time of day should I water grass?
Avoid the middle of the day, when the hot sun evaporates much of the water. Early morning is a common choice.
How long should I run my sprinklers?
Use the tuna-can test: time how long your sprinkler takes to fill a few empty cans with half an inch of water, then water that long twice a week and adjust for weather.
Why is my lawn getting puddles or runoff?
The water may be going on faster than the soil can absorb it, common on clay and slopes. Turn off the sprinkler when it pools and try cycle-and-soak: shorter runs with breaks between.
Do smart sprinkler controllers save water?
WaterSense says replacing a clock-based controller with a WaterSense labeled one can reduce an average home’s irrigation water use by up to 30 percent and save up to 15,000 gallons a year.
Sources
Education only: general information, not professional advice for your home. Building codes, permits and contractor licensing vary by state, county and city, and electrical, gas, roof, structural and tree work can be dangerous, so check the official source we link or hire a licensed professional before you act. We may earn money from ads and, in the future, paid links; our advice isn’t for sale.