Water pressure (PSI) and Gallons Per Minute (GPM) are 2 major factors in what your home’s irrigation system can handle. When planning an efficient automatic irrigation system, you must determine the correct Sprinkler System Design Capacity — how much water is available for residential irrigation.

To check the water pressure, attach a pressure gauge to the outside faucet closest to the water meter. Make a note if the faucet is before or after any pressure regulation. Ensure that no other water is flowing at the residence. Turn on the faucet and record the number on the first line in the right-hand column below. This number is the static water pressure in PSI.

To determine the volume of water available for the system, you need two pieces of information:
A. What size is the water meter? The water meter will generally have the size stamped on the meter body. The most common sizes for residential meters are 5/ 8”, 3/4”, and 1”. In some areas, the water is connected directly to the city main without using the water meter. In these cases, enter the size of the service line.
B. What size is the service line? Measure the outside circumference of the pipe from the city main to the house.

Both of these metrics are important because they let you know how many sprinkler heads a zone can handle as well as how far those sprinkler heads will water.
A GPM example is if your system is giving 12 GPM, and you are using one of our Saturn III 3GPM nozzles, you can have up to 4 sprinkler heads in that zone before you start to lose performance from your sprinkler heads.
A PSI example is if you are using a drip system you will want to be sure that the PSI is under 30 PSI or it could cause your drip lines to blow or give off too much water. In those cases, you can install a pressure regulator to get to the desired water pressure used for drip systems.

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Tags: pressure, Sprinkler, Valve