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Wednesday, May 19th 2004, 12:32pm

Lack of Water Pressure at Sprinkler Heads

I've recently turned on my sprinklers for the year and don't have enough pressure at the sprinkler heads to push them up. There is some water flowing, but not enough. Could it be something with my back flow preventer. I have a Febco model 765. Water is turned all the way on, no other indications of reduced pressure in the house, etc.



Advanced Member

Posts: 53

Location: USA


Wednesday, May 19th 2004, 3:24pm

This most likely a flow rate problem rather than a pressure problem. Your irrigation requires more water flow than your household fixtures. Have you had any plumbing work done since last year? I am assuming that the irrigation system comes off of your house lines. I would check your main shut off valve in the house to make sure that it is on all the way. In my opinion it is not the BF. That would be very unusual.


Thursday, May 20th 2004, 3:35pm

The sprinkler system does come off them main water supply just as it enters the house. The valve is all the way open. I haven't had any work done other than a shower valve leak fixed. I was thinking it was the back flow preventer because that's the only thing between the source and the sprinklers other than the valves. Could the valves be causing the problem? Thanks


Advanced Member

Posts: 53

Location: USA


Thursday, May 20th 2004, 6:02pm

When you had the shower fixed you turned off the house water at that main shut-off? I have came across many situations just as you have described. One of the first things I ask is if there was any plumbing work done. Usually the answer is "yes". You would not even think that would be the problem because everything is working fine in the house. As I stated before, your irrigation system demands more water flow. If that main shut off is just one turn (assuming that it is a gate valve) from being fully open it can/will affect that water demand. Not to seem rude but, please physically check that valve and the ones at the BF one more time to eliminate the possibility of flow restriction. Did you repair that shower or a plumber? The reason I ask is a plumber may have turn down a pressure regulator at the time of service. Is there a pressure regulator on your house main? Let us first verify that all valves are fully open and if there still is a problem we will go to the next step of our trouble shooting process.


Advanced Member


Monday, May 24th 2004, 8:08am

After making sure those valves are open someone should walk him through checking for a master valve.... if the diaphram on that is bad that could affect pressure on all zones... and i've had situations where the bottom plunger in the backflow preventer will freeze and slightly rip and will clog up and reduce a lot of pressure... i know it's not up to code but if u remove it it still works fine


Tuesday, May 25th 2004, 6:20pm

I just checked the main water shut-off valve. Not to YOUR surprise, it was about three turns from fully open!! There's also a regulator, but hopefully the plumber didn't change it. Just checked the sprinklers and they worked just fine.

Great thing this Internet and in particular this forum.

Thanks for the help.

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