# Pex vs. copper, running a new line to water softener.



## Bob999 (Mar 4, 2010)

You should also be aware that the inside diameter of 3/4" pex is significantly smaller that 3/4" copper and this is not generally a good idea on a main water supply line. An additional problem is that the adaptor fittings going from the copper to the pex will further restict the flow because the inside diameter is even less than the pex. If you really need to avoid copper you should consider 3/4 PVC if the code allows it or 1" CPVC because 3/4 CPVC is also smaller inside diameter that 3/4 copper.

You should of course check your local codes and insure that the work you do complies with them.


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## Andy CWS (Apr 27, 2007)

Hi Bob,
Welcome aboard. Glad to see you here.


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## NHMaster (Dec 21, 2009)

Hey there Bob, glad you made it. :thumbup:


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## Gary Slusser (Sep 16, 2008)

ams4life said:


> Hi, i want to add a water softener to the house. The problem is in order to do it, i need to run about 35 feet of line to get the water to where the softener is going to be.
> 
> It's a 3/4 Cu main, pressure is fine all throughout house. I want to stub pex off and want some reassurance that this is the right thing to do.


IMO you should use one continuous piece of 1" PEX instead of 10' or 20' pieces of CPVC or PVC. 

But I wouldn't suggest a 3 valve manual bypass, use the by pass that you can buy with the softener. That type by pass is meant to be left on the plumbing if you need to remove the control valve and resin tank from the plumbing and depending on the brand of softener or control valve, the by pass will have individual ball valves.


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## NHMaster (Dec 21, 2009)

Though 3/4 pex does have a smaller I.D. than copper the fact that you will use far less fittings makes up for any loss that may occur in that particular run. However, I would use Uponor pex and fittings as their fittings are less restrictive than others on the market.


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## ams4life (Mar 4, 2010)

Gary Slusser said:


> IMO you should use one continuous piece of 1" PEX instead of 10' or 20' pieces of CPVC or PVC.
> 
> But I wouldn't suggest a 3 valve manual bypass, use the by pass that you can buy with the softener. That type by pass is meant to be left on the plumbing if you need to remove the control valve and resin tank from the plumbing and depending on the brand of softener or control valve, the by pass will have individual ball valves.


Here's the dilemma, i have access to the tool for 3/4 pex, but not 1". If i had to buy a 1" crimper im thinking that it would not be cost effective. However, if it is a better solution than copper, i might be willin to spend more. I know in the future i will have to replace some more copper in the house (the old section must have old copper, the hot water line to the shower is definantly having flow problems) so when that gets remodeled, i would probly want to switch it over to pexas well. I know that the inside diameter is smaller than Cu, that's why i was worried about running it. However, on a previous post about CU vs pex, one guy ran some numbers and said it came out that pex did not lose any PSI even though it was a smaller diameter because its inside is smoother, and also that its value stays constant, where as copper does not, its weakens as is gets buildup. I wish i could find that post, but i just spent a 1/2 hour looking and couldnt find it. That application was far different than mine though. Nobody seems to be worried about adding 75 feet to the mainline.....should i not be concerned about that? There is one spot i could put it to save alot of feet, but i really dont want to put it there. (in a closet by living room) The softener does have a bypass, i was just putting the manual in for a just in case circumstance....will i lose pressure by doing that? i need shutoffs in case i ever needed to remove it, so i figured as long as i needed those, i might as well add a bypass. i should only need 3 or 4 90's one to get past a foundation wall, one to go up into the room, and one to be able to connect to the horizontal connection. So is 3/4 copper the answer or will this pex be ok? bob didnt like pex on the main line....anyone else have any issues with it? Thanks again for all the advice.


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## NHMaster (Dec 21, 2009)

Pex will be fine and skip the bypass. If you need to bypass you can use the bypass valve in the head.


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## ams4life (Mar 4, 2010)

Thanks a ton....even the 3/4 Pex will be ok? i guess i can just try, if the pressure drops, then i will just have to start over.


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## Bob999 (Mar 4, 2010)

Just to clarify my post--I was not saying there is a problem using pex in a main line. Rather I was pointing out that using 3/4" pex in the main line would give you reduced inside diameter of the pipe and raise the possibility of that you will have reduced pressure at higher flow.

You mention that copper will get build up inside the pipe over time and I am assuming that is one of the reasons you are considering using pex. With the installation of a softener that build would not be expected to occur--the inside of copper pipe carrying soft water will remain clean and without buildup.


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