Using the outside faucet, turned fully on, time how many seconds it takes to fill a one gallon container. Divide 60 by the number of seconds. This is your home flow rate. Plan your sprinkler system and draw it out on graph paper. Plan for proper overlap of the spray to avoid dry spots in your lawn.
Larger heads have larger diameters of coverage which means they require a higher flow rate.
The sprinkler system can use 60 to 75 percent of your home flow rate. If your sprinkler system total is higher than 75 percent of your home gpm, you have to use fewer heads or use smaller heads which have a lower flow rate requirement. Bring this layout with you when you go to buy parts. They are light and easy to work with, plus they won t corrode. The diameter of your pipe is determined by your sprinkler system flow rate.