Hi all, I'm new to the forum and obviously not a plumber so forgive my ignorance here. A contractor is renovating my master bathroom. Where the old shower was, a new vanity will be placed, and a new shower will go to the left of that. When I came home today, it looked as though the contractor is using the existing supply lines for what will now be the bathroom sink and is teeing them off to also run to the new space for the shower to the left. So it appears one of the bathroom sinks and the shower will share the same supply lines. Is that a legit and reasonable way to do this, rather than running new separate supplies to the new space for the shower? If I'm showering and my wife comes in to turn on the sink, will I lose all my shower water pressure or get frozen/scalded? I really appreciate any guidance you can provide here! Thank you!

Not enough info to answer. If your pressure is high enough and the size of the water system ahead of the the old shower line is 3/4" or more, it may be OK. The distance from the meter should also be taken into consideration. Can you post dimensions, distance and Water Pressure?

Thank you for the quick response! The sink and shower are about 100 ft linear from the meter. There does appear to be 3/4in copper pipe in my basement leading into the standard copper lines that come out into the bathroom (those look like 1/2in lines?) As for pressure, I know I need a new PRV so it is high (how high I don't know though). But once that is installed, will it create issues here? Thank you so much!

if the shower has only one shower head and it is a standard water saving flow then you are fine.
even if you are in the shower and your wife turns on the sink next to it, the shower valve will compensate for volume changes.
if you have multiple shower heads and body sprays or if the shower valve is not pressure/volume compensated , you better have a talk with the contractor.

Thank you! That's very helpful and mostly reassuring. We will have one head and one handheld with its own valve so it sounds like we might be ok. We were very clear about our requirements with him but given other things recently I am questioning his integrity and feel I need to validate anything that looks suspect. I just don't have time to find a new guy before our baby arrives so I'm hopeful I can get by with him and a little auditing.



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'good practice' would be separate 1/2 to each fixture from the 3/4 branch/main

your prv will most likely be set for 40-50 'downstream'

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"Measure Twice & Cut Once" - Retired U.A. Local 1 & 638



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