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Monday, May 16th 2011, 10:25pm

Tap outside vs inside

I have a 3/4" water meter in my front yard with a 3/4" copper line that runs into my basement. I have about 11 GPM design flow at 75 PSI but I'd like to have about 15GPM or so...

Rather than tapping the 3/4" copper in the basement, I am thinking about tapping the pipe just after the meter using 1" PVC. Would this give me more GPM or am I stuck with 11?


Supreme Member


Tuesday, May 17th 2011, 10:52am

To avoid water hammer as well as damage to your plumbing (including your indoor plumbing, not just the irrigation system), you don't want water to travel through pipes at a speed faster then 5 feet per second. A 3/4" copper line will reach speeds of 5fps at flows around 7GPM.
Now at my house, I have 1' PVC between the meter and the house (it transitions to 3/4" copper a few feet before the line enters the house). But even if you also have a 1" PVC line to tap into, you're still limited to about 11 GPM through the 1" line.


Supreme Member

Posts: 5,323

Location: Metro NYC


Tuesday, May 17th 2011, 11:56am

You do get more water by bypassing the supply line to the house, when you have a meter near the street


Tuesday, May 17th 2011, 4:07pm


Posts: 4

Location: Cincinnati, Ohio


Tuesday, May 17th 2011, 5:42pm

tap inside or out

There are several advantages to ouside tap, but make sure that the county allows you to tie inside the meter pit. Many counties only allow outside pit. You will gain a bit of flow and pressure, but normally not that much to make difference. As long as you tie in before any regulator on your line in basement (tie in immediately after house shut off) then you will not sacrifice and gallons or pressure. the distance form meter to house is not enouh to make difference unless you have kink in copper line or other obstructions.


Supreme Member

Posts: 5,323

Location: Metro NYC


Tuesday, May 17th 2011, 7:01pm

One big problem with streetside taps is how you place a backflow preventer. Above-ground devices will get tripped over, or stolen for scrap.

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