I would like to install a whole home water filter just after the water tank. The line coming out of the tank to the rest of the house is 3/4in pex. The filter systems that I have looked at so far are all 1/2in connectors. If I use 3/4 to 1/2 adapter to connect to the filter, then another from the filter back to the rest of the pipe system, is this going to cause any negative affects to the water pressure for the rest of the house?

  • If you're comfortable doing the plumbing work yourself then try it - go to the location where you'd install the filter, cut out a short length of the 3/4" pipe and replace it with 1/2". Now go take a shower and have someone flush the toilet ... If you're happy with the result then go ahead & install the filter - otherwise look for another filter with 3/4" fittings.
    – brhans
    Commented May 31, 2018 at 19:28
  • What type of filter did you have in mind? Something like this?
    – Tyson
    Commented May 31, 2018 at 20:03
  • I bought a 3/4" inlet and outlet water filter at Lowes. They also have them at Home Depot and other big bix stores
    – d.george
    Commented May 31, 2018 at 21:49
  • The fitting isn't what will cause the significant flow reduction. The filter media will do that.
    – Matthew
    Commented Jun 1, 2018 at 15:15

2 Answers 2


I would have to question your reasoning for filtering all the water you use in your house. Filtering can get expensive when you start having to replace filter cartridges, especially those rated to take most of the nasty things out of the water. It really is a waste in most cases to be using filtered water to flush toilets, wash cloths, shower and wash dishes.

It is a lot more cost effective to install a filter at one location, such as at the kitchen sink, where water is filtered to a separate valve for drinking, cooking and to feed the ice maker in the refrigerator.

If your reasoning is based upon hard water that has a lot of dissolved minerals or iron in it then there may be better choices to use a water softener rather than a filter.


No. short lengths of slightly narrower ID pipe will not have any noticeable impact on pressure.

  • 1
    Actually it probably won’t effect pressure much, it may drastically affect flow tho, especially since thus is a filter that will reduce flow by nature.
    – Tyson
    Commented May 31, 2018 at 20:00

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.