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 Pipe diameter/water pressure question
Author: dithian (HI)

Hi everyone,

I'm DIY plumbing our off-grid cabin, and I'm using up material I have on hand to do the job. I have a 3/4" pvc line coming into the house (off a 1.5" PVC pipe coming up from my water meter). To get water to a bathroom and a water heater I need to do a run of about 28', then right angle and another 12'. Stubbing up along that route I am servicing a toilet, a bidet, a lav, a washing machine a shower and a bathtub. I have on hand several lengths of 1" copper I'd like to use up. My question is, if I go from 3/4" PVC to 1" copper, then reduce to 1/2" at all the stops (except 3/4 at the water heater), will I be creating problems with my water pressure?

Does the pressure at the end of the line only reflect the pipe diameter at the end point, or will I see a net pressure drop expanding from 3/4 to 1" for a middle segment of the run?

Thanks for your input!

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 Re: Pipe diameter/water pressure question
Author: packy (MA)

you will be improving the piping not hurting it.

you'll be fine

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 Re: Pipe diameter/water pressure question
Author: DaveMill (CA)

Do you have all the fittings and torch to solder the copper, then connect to PVC? Even in high-cost California, 10'sticks of 3/4 PVC are under $4. 1" copper fittings are quite expensive.

Just checking prices here on PlumbingSupply.com:

Copper T 1" x 1" x 1/2" $10.45
PVC T 3/4" x 1/2" x 3/4" $1.37

You might want to save the copper pipe for a future long run.

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 Re: Pipe diameter/water pressure question
Author: sum (FL)

Good point, the fitting cost increase could quickly go beyond the savings from not having to buy 3/4" copper.

Edited 2 times.

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