Lawn Sprinkler Installation

Most inground irrigation systems are divided into circuits or zones to distribute water more evenly. Water pressure is typically insufficient to properly disperse water over the entire lawn at once. A valve operated by an electronic controller operates each zone separately-turning water on and off based on a programmed schedule.

The lawn sprinkler system is made of standard PVC piping extending out from your home's water supply line. A riser is tapped into the PVC pipe where the sprinkler head is attached. Sprinkler heads can throw water in a full circle, a half circle, or quarter circle. Two types of sprinkler heads are available. A rotary sprinkler head is permanently extended above the ground while a pop-up head stays flush with the ground and pop-ups when the water is turned on.

Before installing an in-ground sprinkler system, check with your city or county and obtain any necessary permits. Contact the local utility companies to have them come out and mark where their lines are buried. It is a good idea to create a blueprint of your property and draw in where the utility lines are buried and where your sprinkler system pipes get buried for future reference.

Sprinkler heads will have a throw distance or radius (typically 15'). Ideally you will place the distance between sprinkler heads by the throw distance for 100% overlap coverage (head-to-head coverage)-the water from one sprinkler head reaches all the way to the next sprinkler head. If you live in a windy area, you will need to place the sprinkler heads even closer.

To determine the maximum number of sprinkler heads to use on each circuit, you will need to find out your flow rate. Before starting, make sure all the water inside the house is shutoff. Open an outside faucet all the way to fill a 1-gallon bucket. Note how long it takes to fill the bucket with water. Take the number seconds it took to fill the bucket by 60 to determine the gallons per minute (GPM).

The sprinkler heads will have a GPM rating. Divide the GPM of your supply line by the GPM rating of the sprinkler head to give you the number of sprinkler heads you can have on each circuit. Use only the same type of sprinkler heads on each circuit.

The PVC pipe diameter used to layout circuits should never be larger than your supply line. Typically you will use ¾" PVC pipe for runs less than 100' or 1" PVC pipe for runs over 100'. The PVC pipe should be buried at least 8" underground in a straight and level fashion.

When installing tees for the risers, make sure the risers will be straight up and down at a 90-degree angle. Cut the risers carefully so the sprinkler heads will be at the correct height once fastened to the risers.

Your supply line will connect to a manifold that has a group of control valves. Each control valve is connected to an inground water circuit. A programmable controller is used to allow water to be routed through the appropriate control valve to the inground circuit.

Between the manifold and supply line, you will want to install a stop/waste valve. This will act as an emergency shutoff, but also allows you to drain the sprinkler system for winter. Antisiphon valves also need to be installed on the control valves to prevent backflow of contaminated water into your home's supply lines.

The controller is typically mounted in the garage. Low voltage wires are run between the controller and control valves. You will want to thoroughly test the system prior to filling in the trenches.