# Multiple Shower Head/Water Pressure Question



## Jackofall1 (Dec 5, 2010)

Hello Mike and welcome to the best darn DIY'r site on the web.

It would be good to know what the existing supply line size is and what is the existing line pressure. Without that its hard to say if you will get enough volume. 

Mark


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## MikeDobbs (Feb 27, 2012)

Hi Mark- thanks so much for the warm welcome! :thumbsup:

The main supply lines running in the basement are 1/2" and are reduced to 1/4" copper lines to feed the existing (old) shower head. 

It hadn't occurred to me to check the water pressure although I can say that from my own observations that it is as good or better as anyplace I've ever lived.

I can get to ACE and pick up a pressure gauge in the next few days to measure it directly though- didn't even realize they made those.


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## joecaption (Nov 30, 2011)

Sounds like somethings wrong already. No way unless someone did something really wrong is a shower head supply 1/4"
Even a sink would have 3/8 supplys.
It will do 0 good to check the pressure. At rest the pressure will always be whatever the the incoming pressure is. It's volume that matters.
If your running two heads I would replace all the supplys with 3/4" it should increase the flow by about 25 %.


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## Jackofall1 (Dec 5, 2010)

joecaption said:


> Sounds like somethings wrong already. No way unless someone did something really wrong is a shower head supply 1/4"
> Even a sink would have 3/8 supplys.
> It will do 0 good to check the pressure. At rest the pressure will always be whatever the the incoming pressure is. It's volume that matters.
> If your running two heads I would replace all the supplys with 3/4" it should increase the flow by about 25 %.


Pressure has everything to do with flow, without it you will not have flow.

If the inlet pressure is 75 PSI then you will have approximately 5 GPM @ 60 PSI at the valve assembly, allowing for 30' of 1/2" pipe. 

A new shower head is designed to used 2.2 GPM so as you can see, you could run (2) heads with a 1/2" pipe but don't flush the toilet or turn on a tap at the sink.

But for a multihead shower I to would be looking at running a 3/4" up to the shower and then splitting from there.


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## ben's plumbing (Oct 6, 2011)

MikeDobbs said:


> I am re-doing an old bathroom and installing a larger shower with two shower heads (actually two shower stations, each with a rain head, and several smaller jets on the wall which can be turned on or off).
> 
> My question is whether I should run a new hot and cold supply line for the second shower head, or if it sufficient to simply split the existing lines and run them to each head. My concern is that if I split the existing lines I won't have enough pressure to run both heads.
> 
> ...


before you go any further read the instructions for the shower stations...they have specs as to what is required to run there product after getting the requirments see if house is able to comply with demand???? ben:yes:


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## MikeDobbs (Feb 27, 2012)

OK- I feel pretty stupid because I gave the wrong pipe dimensions. :blush:

You are correct- the main pipes in the house are 3/4", those are split down to 3/8" to the shower head.

Checking the manual for the shower panels I find:
"2.38 gallons per minute at 43 pounds per square inch (PSI)"​To run both of them I'd want about 5gpm- so would the recommendation be to run new 3/4" supply lines (hot and cold) to the shower and split them just before the connections to the shower panels?

If this is the case- can anyone comment on whether it is permissible to run these supply lines horizontally through the wall? The room I am working in is on a concrete slab, and to run new lines under the ground feels like an imposing job to me. If I can run horizontal through the wall, I can bring the pipe from the basement into the wall, and then run them horizontally to where the shower is.


Thanks to everyone for the help with this- tonight is my first night on the forum and I can see I'll be visiting regularly as I work through this remodel! :thumbup:


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## ben's plumbing (Oct 6, 2011)

MikeDobbs said:


> OK- I feel pretty stupid because I gave the wrong pipe dimensions. :blush:
> 
> You are correct- the main pipes in the house are 3/4", those are split down to 3/8" to the shower head.
> 
> ...


hey mike don't feel stupid your doing fine...3/4 supply will be fine... yes you can run through wall...you may want to check incoming pressure to be safe...ben


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## joecaption (Nov 30, 2011)

Still have never once seem a shower head with a 3/8 supply or feed.
1/2" min. 
It will work fine being run horizontal.
Feed it with 3/4" lines and split off with 1/2" for the heads.


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## Javiles (Dec 12, 2011)

Hey guys I think what he’s installing is the pre piped shower stations they hang on the wall with the main shower head then a couple of body spray below they rough at ½ inch then you would use 3/8 flexible supply lines to connect to the station, so you can pre-pipe then hang on wall. I’ve installed a couple of them don’t really care for them. Pressure and volume is still an issue.


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## joecaption (Nov 30, 2011)

3/8 supplys to a shower head? Hmm.


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## Javiles (Dec 12, 2011)

joecaption said:


> 3/8 supplys to a shower head? Hmm.


The 3/8 supply the assembly, inside the body it goes to 1/2 inch like i said don’t care for them. You can use 3/8 or 5/8 flexible breaded supply 5/8 harder to work with, they recommend 3/8 remember this thing mounts after the finished wall no way to pipe it in from behind after rough,


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## joecaption (Nov 30, 2011)

If that's what the OP really has that's one poor set up.
Stand on a 3/4" garden hose and see how that works out for you trying to wash your car.


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## Javiles (Dec 12, 2011)

I could never understand what people see in them they look like robots in the shower, I mean if your tearing down the shower go with the multi control multi shower heads and body wash heads, this is where the plumber needs to know how to loop and manifold rough.


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