# 5 GPM @ 36psi static



## DiabeticKripple (Apr 14, 2019)

Hey guys,

Looking at designing a sprinkler irrigation system.

I only have 5 GPM @ 36psi (static) through my hose bib.

Main supply into the house/meter is 3/4" copper pipe. It goes up to the ceiling to the cold water manifold, where it turns to 1/2" PEX to the wall outside.

I'm thinking that the 5 GPM isn't enough to support more than 2-3 heads per zone which I don't think will be enough.

Should I be looking at getting a plumber in to tee off the 3/4" copper and run another 3/4" line to the wall just for the irrigation?


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## Crabbychas (Apr 25, 2018)

You should definitely have a plumber put a tee in your main supply line.


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## SCGrassMan (Dec 17, 2017)

Crabbychas said:


> You should definitely have a plumber put a tee in your main supply line.


Seconded. 1" PVC to a good backflow. I will bet you a cup of coffee you'll get at least 10 GPM if it's city water.


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## craigdt (Apr 21, 2018)

It probably wont be enough.

I agree with the above gentlemen.

You could also look into your hose bib. I had a really nice quarter turn, frost free faucet.
But it restricted flow to about 5gpm at 35 PSI.

I put a 3/4" ball valve on there and it went to something like 11GPM at 55PSI.


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## DiabeticKripple (Apr 14, 2019)

I was thinking of running a 3/4" copper line to the wall.

Right after the tee i would like to put a 3/4" ball valve and then the backflow preventer. Keeps them inside where they can't freeze.

Outside I would put another 3/4" ball valve as the shutoff valve. For winterizing that valve I would just have to close the ball valve inside the house and open the one outside so the line can drain.

Something I might be able to do myself to save some $$$


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## boltfanindenver (May 2, 2019)

Thanks for this feed, I think I may have to tee my main as well. I have good pressure at like 58PSI but im only getting like 4GPM outside. 
The original house was built in 1894, but in 2005 a previous owner did a big renovation and replaced everything. So the water comes into the house off the city line via a 1" galv steel pipe. From there it goes into 3/4" copper for like 12" with a ball valve as my main shut off in the house. Then it goes into 3/4" pex the rest of the way to offshoot that they installed I assume with the intention of having it be the sprinkler line since there's another ball valve inside then about 2' of 3/4" copper that goes through the wall and was capped outside. 
I assembled a little manifold with a pressure gauge followed by a ball valve as suggested by a youtube video from Ewing sprinkler supply ( https://www.youtube.com/watch?v=eEfyFiOUeUA ), and partially opened the gauge until It was moving at 40psi (the suggested pressure for the sprinkler heads I want to use) and at 40psi I only get 2 GPM...which would mean i need like 8 zones for my 2890 sqft yard.


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## SCGrassMan (Dec 17, 2017)

If there's a good reason not to tee into your main for irrigation, I don't know what that would be.


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## Long Island Lawn (Sep 20, 2018)

Teeing into the main is fine but You need a backflow preventer after rthe tee so the irrigiation water cant flow back into the houses potable water. So to tee into water without a BP would be an issue . Please anyone correct me if im wrong.Teeing into the main is fine with a backflow preventer.


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## DiabeticKripple (Apr 14, 2019)

Long Island Lawn said:


> Teeing into the main is fine but You need a backflow preventer after rthe tee so the irrigiation water cant flow back into the houses potable water. So to tee into water without a BP would be an issue . Please anyone correct me if im wrong.Teeing into the main is fine with a backflow preventer.


That's code in most places.

My plan was right after the tee is a ball valve, then a full bore dual check valve. Run to the wall and out to another ball valve and down into the valve box. Then it's 3/4" all the way with 0 restrictions past the town flow meter.


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## SCGrassMan (Dec 17, 2017)

Long Island Lawn said:


> Teeing into the main is fine but You need a backflow preventer after rthe tee so the irrigiation water cant flow back into the houses potable water. So to tee into water without a BP would be an issue . Please anyone correct me if im wrong.Teeing into the main is fine with a backflow preventer.


You need a backflow preventer whether there is a tee or not. That's just part of system design.

I personally like the Zurn 975 XL2 1" model.


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