Fixing misty sprinklers … a simple way to save water

Sunset, August, 1990

Fixing misty sprinklers . . . a simple way to save water Modern sprinkler systems are designed to operate best at very specific water pressures--usually about 30 pounds per square inch (psi). When the pressure's too high, water is thrown far of its target or becomes mist that blows away; low pressure throws water too short a distance.

Even with a system pressure regulator, though, it's rare that each sprinkler gets exactly the right pressure. Reasons for this are simple: water pressure is inversely affected by changes in elevation (nearly 1/2 psi for every foot), and by how many sprinklers are on the circuit. Also, residential water pressure usually fluctuates with time of day and with season.

But it's easy to fine-tune individual sprinklers--if the system has plastic heads and was installed in the last 10 years or so. Pressure-compensating devices or screens like the ones below are available from two major sprinkler manufacturers. The devices operate at system pressures between 30 and 70 psi. They're easiest to add as you're installing a new system, of course, but not much more difficult to fit into existing ones.

In most cases, use the device that matches the amount of water each nozzle is designed to deliver. You can also use these devices to customize nozzle performance for small areas by undersizing the delivery. For example, a 180[degrees] nozzle with an 8-foot throw normally requires a 0.9 gpm screen; if, instead, you use a 0.3 gpm screen, its pattern narrows to 160[degrees], with a 3-foot throw. Suppliers can give you specific help with customizing.