On Sep 13, 6:30 pm, " wrote:
all the water lines inside my home are 1/2 inch, although the outdoor
supply is 3/4

we have a single copper 1/2 inch line servicing the bathroom. it
supplies the toilet sink and finally the shower

if someone flushes the toilet while someone is in the shower they get
burned.

Aahhh,.... Why don't you lock the door when you're
in the shower so no one can use/flush the toilet?
A whole lot cheaper fix!