Proper underground sprinkler installation begins with good planning. Depending on the area, building permits might be required, and installers will be expected to adhere to all building and plumbing regulations. A call to the local utilities companies also will be required to ensure that no cables or gas lines are in the way during the sprinkler installation.
Sufficient water pressure and rate of flow should be confirmed before beginning sprinkler installation. Sprinklers need a minimum water pressure of 20 pounds per square inch (138 kilopascals) and flow rate of 60 gallons (about 225 liters) per minute. A water pressure gauge, available from many outlets for purchase or rent, is required to determine water pressure. Counting the number of times that a bucket – any size will do, if the bucket’s volume is known – can be filled in a one-minute period will help determine the rate of flow.
Even if these minimum requirements are met, residential water pressure often is insufficient for watering an entire property at once. Instead, the property should be sectioned off into zones of approximately 1,200 square feet (365 square meters), each with its own circuit. The water supply can then be directed to the desired zone, one at a time.
A scale diagram of the property can be especially valuable for sprinkler installation. For good coverage of a lawn, sprinkler heads should be placed 7 to 10 feet (2 to 3 m) apart. This diagram also will offer a good estimate of the number of heads, the length of pipe and the other supplies that might be needed for the sprinkler installation. Next, stakes and string are used to mark this layout on the lawn.
When digging trenches for the pipeline, one should begin with the main lines, then branch lines. These trenches should be as straight and level as possible. All trenches should be 8 to 10 inches (20 to 25 cm) deep, and sod should be lifted out and kept for covering the pipes later.
Pipes and zone valves should be assembled using solvent cement above ground before setting them into the trenches. Reducing tees will need to be installed for each sprinkler head. Care should be taken to ensure that the sprinkler head just reaches the top of the trench.
To tap into the home’s plumbing, a manifold will have to be installed. The tee connecting to the water supply should be attached just past the water meter. The control box is then wired to the valves and installed in the home. After the system has been tested and works properly, the trenches can be filled in with sod, and the sprinkler installation is complete.
