Sprinkler system water pressure too high


Old 08-04-12, 11:00 PM
Thread Starter
Join Date: Aug 2012
Posts: 2
Sprinkler system water pressure too high

Hi all,

Our sprinkler system was set up about 8 years ago. The lawn covers roughly a 20'x20' area, and there are about 16 sprinkler heads, separated into two valve systems with 8 sprinkler heads on each. When I run them both simultaneously, manually, the coverage is perfect, the areas covered by each station intersect so that most of the lawn is covered.

But when we use a timer (a Rainbird ISA 304), each valve is operated individually so the radius of each sprinkler head is doubled. The pressure seems to double so the system ends up watering tree trunks, the siding of the house, sidewalk, and it misses lots of areas where there is actual lawn. W hen I try to tighten the valve on each sprinkler head to reduce the water flow, the pressure builds up to too much and it is so powerful that it flushes out individual sprinkler heads.

I've looked into running two valves simultaneously on one station on our timer -- but right there in the manual is a huge warning that connecting more than one valve to one station could destroy the timer.

Any suggestions what to do? Has anyone seen this problem before?

Thank you in advance,
Serena M.
Santa Clara, California
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Old 08-05-12, 05:35 AM
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Join Date: Mar 2003
Location: NC, USA
Posts: 18,562
Most sprinklers are designed to work with a max pressure of 40psi while its possible you have 80 or 100 psi from a city water supply. I would install a pressure regulator in the system. There are ones that go in the supply line to the sprinklers and would regulate the pressure for the whole system and there are pressure regulating spray heads so you can adjust each sprinkler individually.

In line pressure regulator
Rain Bird PRS-Dial Pressure Regulator

Pressure regulating sprayer.
Rain Bird 1800-PRS Spray Heads with Built-in Pressure Regulation

Modern codes require homes to have a pressure regulating valve. I wonder if you have one? It helps to isolate your house from pressure fluctuations in the water supply. It is possible that the city has made changes in the water system that have increased the pressure of water supplied to your home.
Old 08-07-12, 12:48 AM
Thread Starter
Join Date: Aug 2012
Posts: 2
Thank you so much for this info. At the very least, this confirms my suspicion that something is not ideal with my water pressure and sprinkler system design. I'm going to pursue the sprinkler system-wide pressure regulator and will look into the water pressure regulator valve for the entire property (and whether we have one).

Thank you again!
Santa Clara, California

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