# What size piping



## h22lude (Jul 24, 2018)

My house is on a well. I had a new pressure tank installed recently with some filters for the house. I had the well company use 1" PEX from the pressure tank to the filters and install a ball valve prior to the filters so I can use that to install sprinklers. I want to test what my pressure and water flow looks like from that valve. What size tubing should I use to test this? I read on irrigation tutorials that 1 1/4" PVC is good to use when the main line is 1" but then use 1" after the valves. Should I use 1 1/4" PVC at the main or stick with 1"?

I've been using my spigots and homemade sprinklers with MP Rotator nozzles. I get really bad pressure after two sprinklers in line. I'm thinking this is a combination of the PEX pressure loss and the spigot being restrictive. I'm hoping tying into the 1" PEX using PVC will help with the pressure issue.


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## TSGarp007 (May 22, 2018)

Just looking to test your gpm and pressure? The irrigation tutorial should cover you pretty well, but I'm guessing you just want to use a pipe with an interior diameter (ID) at least as big as the one the water is coming in on. In your case 1" class 200 PVC or Schedule 40 PVC, which I'm guessing you were considering using, are both bigger than the 1" PEX I think.

Make sure you leave some gpm for your toilets, etc. if your house shares this well, or I guess just water in the middle of the night.


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## g-man (Jun 15, 2017)

1in PEX is like 3/4 copper. How much can your pump/well do?


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## h22lude (Jul 24, 2018)

TSGarp007 said:


> Just looking to test your gpm and pressure? The irrigation tutorial should cover you pretty well, but I'm guessing you just want to use a pipe with an interior diameter (ID) at least as big as the one the water is coming in on. In your case 1" class 200 PVC or Schedule 40 PVC, which I'm guessing you were considering using, are both bigger than the 1" PEX I think.
> 
> Make sure you leave some gpm for your toilets, etc. if your house shares this well, or I guess just water in the middle of the night.


Yeah I was look at the tutorial. That's where I read to use 1 1/4" pipe.

I water at 5am right now


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## h22lude (Jul 24, 2018)

g-man said:


> 1in PEX is like 3/4 copper. How much can your pump/well do?


I'm not sure right now because I don't have a good way to test. I want to use something similar to what would be used for irrigation. I think teh 3/4" PEX throughout the house is a little too restrictive to get a good measurement


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## g-man (Jun 15, 2017)

Even if you T from the 1pex to something larger, you will be limited to 12gpm because of the 1in PEX.

Do you know the pipe size out if the pump?


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## TSGarp007 (May 22, 2018)

How long is that 1" pex line from the tank to the ball valve?


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## h22lude (Jul 24, 2018)

TSGarp007 said:


> How long is that 1" pex line from the tank to the ball valve?


It is right at the tank. 3ft maybe.


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## RVAGuy (Jul 27, 2020)

Here's the thing about piping pressure losses. It is entirely dependent on the length and the fittings used in the system. Keeping in mind this is a logarithmic scale in the chart above, the pressure difference between say 12GPM and 18GPM is a difference of 3.75 - 2.00=1.75 ft of head per 10 ft. For 3 feet of pipe that equate to approximately a 0.23 PSI (not ft of head) pressure drop difference if the flow was increased to 18 GPM.

Moral of the story: for such a short run of pipe, the 12 GPM is a good guideline, but it's just that. Note however if you read the chart the pressure drop is much lower for 1 1/4" piping at even 20GPM (blue circle).


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## TSGarp007 (May 22, 2018)

Pretty detailed response @RVAGuy, that's why I was asking the length.


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## RVAGuy (Jul 27, 2020)

@TSGarp007 It was a good question. I do this sort of stuff at work, so I can get really into the weeds about piping pressure losses and the sort.


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## g-man (Jun 15, 2017)

Great chart. Looking at the difference between 1in and 3/4in at a given gpm (eg. 10gpm) is very telling.


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## Justin9314 (Jan 22, 2020)

just my .02... I recently built a home and designed the well for irrigation. Unfortunately, the builder and well company didn't communicate so they put 1" line from the pump to the tank. This severely limited my desire for irrigation so the well company created a T straight off the well with a 2" ball valve in the ground. While it is not indoors, it gives some pretty awesome GPM and PSI. If your system cannot run off the 12 GPM cap that 1" pex has, maybe see if this is an option. It has worked well for me. I just covered the extra piping with a fake rock.


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