Grassy lawns are notoriously thirsty. An emerald green lawn may be a traditional sign of American success, but the water Americans use to get there is pretty outrageous. According to the Environmental Protection Agency, landscape irrigation accounts for “nearly one-third of all residential water use, totaling nearly 9 billion gallons per day.” That is a tremendous amount of water. But what makes that number even more disturbing is that at least 50% of that water—4.5 billion gallons—is wasted. Inefficient irrigation practices, including overwatering, runoff, and unnecessary evaporation, account for billions of gallons of potable water used each day without providing even the smallest bit of nourishment for thirsty plants. Given the amount of water we lose every day to waste, efficient irrigation can make a massive difference in our overall water consumption. If even half of that waste was avoided, we could save 2,250,000,000 gallons of water a day, enough to provide for over 20,000 households.
Know Your Irrigation System Output
Before you can get started with efficient irrigation, you need to know your existing irrigation system’s output. Typically, a grass lawn needs no more than one inch of water each week. That water can come from rain or artificial irrigation. To make sure you aren’t overwatering, you need to know how much water your irrigation system or sprinklers put out per minute.
The easiest way to test this is to use six to eight small, flat tin cans placed around your lawn. Tuna cans are a perfect size. Run the sprinkler for 15 minutes, then measure how deep the water is in each can. Add the depths, then divide by the number of cans to determine the average amount of water output in 15 minutes. Once you know how much water you get in 15 minutes, you can do the simple math to determine how long it takes your sprinkler to put out one inch of water. For example, if your sprinkler puts out one-quarter of an inch of water in 15 minutes, you will need four times that, or one hour, to spray a full inch of water.
Remember that you only need to water when if the lawn has not already been naturally irrigated. Keep a small rain gauge somewhere on your lawn. Check it before watering your lawn. If there are at least three-quarters of an inch of water, there’s no need to irrigate again.
Water at the Right Time
When you water will have a significant effect on how efficient your irrigation is. Certain times lend themselves to more water loss and waste. For example, watering in the second half of the day, when the sun is hottest, will result in more water lost to evaporation. Similarly, watering when it is windy will result in water lost to evaporation before it can hit the ground. If it has rained recently, there is also no need to water.
The best time of day to water is in the early morning before the heat of the day. Watering in the morning when it is still cool lets as much water hit the ground and stay there long for the soil to absorb it. Keep in mind that although watering when it is cooler is better, you shouldn’t water in the late afternoon or evening. It is preferable not to water when the sun is high, but you don’t want the sun to set on your wet lawn either. The water may sit on the lawn overnight, creating an opportunity for fungi and other turf diseases. Instead, water in the morning when the water has time to absorb, but excess water will evaporate in the sunshine.
Runoff is one of the greatest contributors to the 2.25 million gallons of wasted irrigation water every day. Simply put, runoff is the result of applying too much water too quickly. Depending on your soil, the ground may not be able to absorb the full inch of water it needs in the time it takes your sprinkler to put out an inch of water. If the water is pooling and running off, pause irrigation to let the water soak in. Once the water has soaked into the soil, resume watering until you have reached the amount of time it takes to put out one inch of water.
Clayey and compacted soils are notorious for their inability to absorb water quickly. If you have clayey or compacted soil, you will almost certainly need to break up your weekly irrigation into two periods with a short break in between. The break gives the soil a chance to absorb the water before you continue. Another way to maximize and speed up water absorption is to aerate your lawn. Use a core aerator to pull out plugs of dirt from your lawn. The aerating loosens the soil and gives water direct access to the plant roots.
Runoff can also cause pollution issues when it drains into local waterways. Runoff from your lawn can carry fertilizer, animal waste, and other nutrient-rich pollutants. When these pollutants reach local waterways, they can cause algae blooms that choke out the naturally occurring wildlife and damage the ecosystem.
Pick the Right Sprinkler
The type of sprinkler you use has a strong effect on the efficiency of irrigation for your lawn. Typically, oscillating sprinklers that shoot water high in the air are the least efficient because much of that water never hits the ground. It is lost to wind and evaporation in mid-air. To avoid those problems, you need a strong, directed water spray with large droplets that go directly to the ground.
The gold standard of water-efficient sprinklers is the impact sprinkler. That’s the clicking, rotating sprinkler you may have seen installed in some homes. Its efficiency comes from the fact it puts out a strong jet of water close to the ground. The water is moving quickly, so it does not evaporate, and the spray is low to the ground, so it goes directly to the soil without further evaporation.
The next best type of sprinkler is a rotary sprinkler. It puts out a similar flow to the impact sprinkler, strong and low to the ground. If you need to get water to a tight area, consider a soaker hose attachment, which is basically a glorified watering can.
Going off the (Water) Grid
Solar panels are a great way to get off the power grid and save electricity. But did you know you can get your lawn off the water grid? The thinking is simple. When it rains, you usually get a lot more water than your lawn needs. And even if it doesn’t rain a full inch, if you collect all the water that falls on your home, you might have enough to irrigate your lawn for the week or longer. Of course, you can’t always rely on the rain to fall. But you can collect the excess rainwater to use later.
For thousands of years, long before there was running water, people collected rainwater in cistern, barrels, and other containers to use later. While modern hygiene standards may not recommend untreated rainwater for human consumption, your plants aren’t quite so picky. And it’s easy to collect the rainwater. The simplest thing to do is to purchase a rain collection and storage kit. You can get them at most big box home improvement or garden stores. A hose or pipe attaches to your gutter downspout and directs water into a large barrel, which is covered to prevent contamination and evaporation. At the base of the barrel is a nozzle where you can hook up a hose. Once the hose is attached, it can be connected to a sprinkler just like you would when connecting to a regular spigot.
Rain Collection Considerations
If you plan to use a rainwater collection system, be aware of a few things. First, check your local laws and regulations. Not all jurisdictions allow rainwater collection, so make sure it’s legal before you start. Second, it is crucial to keep a screen on your downspout and a cover on your water barrel. The screen keeps leaves out of the pipe to the barrel and, by extension, out of your water barrel. The cover keeps out any kind of contamination, including insects, small animals, and birds.
Efficient Irrigation for Your Lawn: Summary
Water is cheap to buy, but the demand is often higher than the supply. Water is a critical natural resource, and Americans waste over two million gallons every day as part of their landscape irrigation efforts. To save water, you need to take advantage of efficient irrigation for your lawn. That means testing your irrigation system and watering for only as long as it takes to put out one inch of water. If it just rained, you can skip irrigation altogether.
Avoiding runoff by watering in shifts conserves water and avoids pollution. You can also minimize evaporation by watering in the earlier, cooler part of the day and using an impact or rotary sprinkler. Rainwater collection is another option to conserve water when it rains and spread out the bounty over several drier weeks. Of course, water efficiency also has a lot to do with the turf itself. High-quality turf, like the turfs sold by The Turfgrass Group, is more efficient and requires less irrigation than other similar turf varieties. You can find a grower in your area here.