Testing

• Buy a pressure gauge that will fit on a garden hose connection. You will be able to find one in the irrigation supply section of most home centers. Thread the pressure gauge onto an outside faucet, near where you are planning to connect to your home's water supply. Turn the faucet on and the dial will indicate the available water pressure. Now take a 5-gallon bucket and time how long it takes to fill it. Divide 300 by the number of seconds it takes to fill the bucket and you have the number of gallons per minute your water system can deliver. Working within the limits of your pressure and volume findings will ensure a successful design.
  
  

Planning

• Sketch out your yard and any beds you plan to water with the system. Working with the performance charts from the sprinklers you've decided to use for the job and the pressure and volume results from your testing, lay out the sprinklers on your sketch with each sprinkler set up so that its radius of reach just touches the heads to either side and directly across from it. This is called head-to-head coverage, and is vitally important to a successful system. Larger areas will require gear-driven rotors. Smaller areas will require fixed head sprayers.
  
  Once you've laid out the sprinklers, calculate how many sprinklers you can have on each zone valve, based on the GPM of each head. For example, if you have 15 GPM available at 35 PSI and the watered area in one section of your yard is 35 feet wide, using Rain Bird 5000 rotors and covering a half circle with each, each rotor will consume 3.33 GPM. This means you can have 4 heads per zone and maintain performance.
  
  Once you determine all your zone divisions, you can sketch your plumbing tree, showing the main trunk line, valve lines and the lines from the valves to the sprinklers.
  
  

Installation

• The brain work is over and now it's time to put your back into it. Begin by installing your point of connection. In some areas, backflow preventers are required for irrigation systems that tie into municipal water supplies. Check these regulations before your cut into your home's water supply line. You may be required to have a licensed plumber install your point of connection.
  
  Locate your controller where it is convenient to you from the lawn. Just inside the garage is a popular location. The controller also needs access to an electric socket.
  
  Rent a trencher to dig the paths for all the water and electrical lines. Water and electric lines should be about 18 inches deep throughout the project. Be sure to have all utilities located and marked before you start digging.
  
  Assemble each zone completely from the valve to the sprinklers. Flush the lines, install nozzles and test each zone as you go.