# GPM Design Help



## DTC (Jun 8, 2018)

My water service is split right after the meter: to the irrigation system and to the house. The key point here is that my irrigation system does not enter my home plumbing, where there is a whole-house pressure reducer and 3/4" inside-wall plumbing. How can I deduce my GPM given the known variables?


The water meter is 3/4"

The irrigation system's service line is 1"

The static nominal pressure at the street is 125 psi, with a min of 119 psi

Am I right that checking the pressure on the home's spigots and doing a bucket test are not applicable here?


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## RVAGuy (Jul 27, 2020)

Since it sounds like you already have an irrigation system set up, is there a reason you can't tie into one of your zones and get a GPM from one of the heads? Specifically removing a head, threading a PVC union onto the PVC connection under the head and using that GPM? If anything it will be a low (a conservative estimate) but will give you something to start by.


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## Colinwjholding (Apr 6, 2020)

Ya just throw a 90x1/2" or 1" tee x half and put a 1/2 hose bib with a pressure gauge. I like using the hose bib for my stuff because i re ruse it at work.


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## Colinwjholding (Apr 6, 2020)

Also if you have that much pressure in 3/4" meter I guarantee you will get the full 16 gpm out a 1" line


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## gorgedude (Jul 5, 2020)

I'd have to see your set up but if you have a blow out valve on your manifold you can just thread in a pipe to that and do a bucket test. I'm on city water with 3/4" coming off the main line before the house and I'm at 12gpm.


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