How Many Sprinkler Heads Per Valve?

Checking Water Pressure

• Before you go about designing your sprinkler layout, it's critical to understand how much water pressure is available inside your home's plumbing. Check your water pressure by screwing a water-pressure gauge onto an outdoor faucet. Turn the water on all the way at the tap and read the gauge. Ensure no water is on anywhere else in the house while you take your reading. Write down the point where the needle lands on the gauge. This is the PSI reading, or pounds per square inch.

For Standard Pressure

• Most residential sprinklers include sprinkler heads spaced out about 10 or 20 feet apart. Each sprayer will cover between 20 and 50 feet. And, each sprinkler zone installed on a system with an average of about 30 PSI will support up to eight sprinkler heads. That means a home with an average PSI of 30 will cover a maximum of 400 square feet. Installing any more than eight sprinklers on an average system will cause water pressure to drop to all of the sprinkler heads, and water may not cover the entire area that the heads are supposed to.

For Higher Pressure

• Some homes not on wells can have water pressure of up to 60 PSI. This is considered to be on the higher end of available water pressure. You can take advantage of this by installing up to 15 sprinklers per valve. The higher water pressure will enable each of the sprinklers to deliver water across their designed limits, covering your lawn with an even layer of water. Some sprinklers that use smaller supply pipes will not be able to support 15 heads, however. It's generally recommended that you use larger pipes -- 1 inch in diameter -- if your available water pressure is near 60 PSI, to get the maximum benefit from the pressure.

Adjusting Water Pressure

• In some cases, the amount of water pressure available to your home is not the amount that leaves your taps. That's because of a device called a water-pressure regulator. These devices are installed along the main water line and regulate how much pressure is allowed into your lines. You can adjust this regulator to increase the water pressure to your system, thus increasing the number of sprinkler heads per valve. Loosen the nut around the top of the regulator with a wrench and turn the screw on the top of the valve clockwise to increase the water pressure. Check the performance at the tap with a water-pressure gauge before committing to the number of sprinklers per valve.