ok, we have a 5x5 shower that has one shower head. we are about to rip all the old tile out and put up new durarock and tile. in the process we were wanting to add a second shower head directly across from the first and also add a hand shower on the back wall. what do i need to do to ensure proper water pressure when i tee the other two lines off the main one?
Hopefully, you can come off of a 3/4" main line for the two 1/2" tees for showerheads. If you try to run two showers with one 1/2" line, you will greatly lack pressure. The handheld could be taken off one of the shower supply lines since it probably won't be used at the same time as the showerheads. On new construction of this type, we run a 1" main for multiple showerheads. Hope you have a large water heater also.
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