I am replacing an old baath, which has been sunk into the floor (ground floor of a bungalow, as an aside they mades a real pigs ear of fitting it, cutting all the floor joists off to let the bath rest on the bathroom floor. I am about to replace the joistsm and fit a conventional bath. The piping to the old bath i tink is 3/4in, Is it Ok to supply a bath through 15mm pipework or should it be 22mm, I appreciate that using the smaller diameter will cause a reduced flow rate, but that isnt a problem.