Thoughts on downsizing pipe

Old 01-27-16, 03:29 PM
Thread Starter
Join Date: Mar 2010
Location: Arkansas
Posts: 3
Upvotes: 0
Received 0 Upvotes on 0 Posts
Thoughts on downsizing pipe

Need some advice on a potential upcoming project.

I am looking to install a water softener. The main line coming into the house is 1" copper. I am looking to branch from that to the water softener with pex, and then return to the 1" copper (about 100' round trip). Would there be any problem using 3/4" pex for this? I have city water, 2.5 baths, water pressure is 80+ PSI, and never had issues with drops even during high demand.

Appreciate the help!
Old 01-27-16, 03:48 PM
Join Date: May 2015
Location: USA
Posts: 3,107
Received 145 Upvotes on 118 Posts
1" copper has a design flow rate of about 5 to 10 gallons per minute. This is based on limiting the speed of water moving through the pipes to 2-4 feet per minute, which controls pressure drop and pipe wear.

3/4 PEX has design flow rates less than half of those for 1" copper. This is offset somewhat by fewer fittings and other restrictions compared to copper. You will also have about 10-15 PSI pressure drop across the softener. OTOH, you are starting at 80 PSI which is higher than normal residential pressure.

Still, on balance I'd recommend using 1" PEX to avoid noticeable flow reduction. If the runs were shorter it probably wouldn't be a big deal, but your round trip is pretty long.

Let's see what others here have to say.

Thread Tools
Search this Thread
Ask a Question
Question Title:
Your question will be posted in: