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New Member


Wednesday, September 30th 2015, 6:48pm

3/4 valve, what size poly pipe should I go with 1/2 or 1?

I have a 3/4 inlet from the main water supply and 3/4 valves. Should I go with 1/2 or go up to 1? I have 6 sprinkler heads. First time posting. I searched through the main topics and can't find the answer. Thank you.




Wednesday, September 30th 2015, 8:30pm

What is your PSI and GPM?


New Member


Wednesday, September 30th 2015, 10:17pm

PSI is 70 and GPM is 18




Wednesday, September 30th 2015, 10:46pm

For the poly pipe, are you talking about the mainline (the line that goes to each valve) or the laterals (the lines that go after the valve to each sprinkler head)?


New Member


Wednesday, September 30th 2015, 11:08pm

thanks, I'm talking about the laterals. The mainline is 3/4 and the valves are 3/4.


Active Member

Posts: 36

Location: Knoxville, TN


Wednesday, September 30th 2015, 11:20pm

I would strongly advise that you go with 1" for the mainline and possibly even 1" for the laterals. You are also working that valve over with 18 GPM flow.

I will note, that I am not in the irrigation field, I just looked up some charts and learned some stuff by reading, even still, I am pretty sure you are severely limiting your system.


Supreme Member

Posts: 5,298

Location: Metro NYC


Thursday, October 1st 2015, 6:59am

PSI is 70 and GPM is 18
You will likely never get 18 gpm to pass through any 3/4-inch zone valve (unless it's a true one-inch valve with reduced-size inlet threads) - at any rate, a flow beyond 10 gpm would be best handled by 1-inch pipe


Advanced Member

Posts: 111

Location: Omaha, Nebraska, USA


Thursday, October 1st 2015, 9:48am

1" pipe. Definitely. You should also consider nozzling your heads down to 1.5GPM each


New Member


Thursday, October 1st 2015, 10:18am

Thank you All!!!

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