by acsimpson »
Mon Sep 28, 2009 4:36 pm
I would expect that under mains pressure 15mm would be reasonable, but this obviously depends on the mains supply. Has your plumber given reasons for his desire to use 15mm? It may just come down to cost, in which case if you are the customer are willing to pay extra for a chance at a better end result I would expect the plumber to be willing to do it.