My friend has asked me to install a bath/shower mixer in his council flat. The flowrate to the bath taps for the cold is twice that of the hot and I am want to avoid problems the unbalanced supplies will cause re using the mixer. It would be possible to fit a service valve on the cold supply pipe with a view to reducing the flow to that of the hot, but having checked the existing pipework I have found that the cold section is run in 22mm, but the hot section (from a combi boiler) is run in 15mm. This should be changed but should the local council be responsible for this work? I should add that my friend is partly disabled? Any views appreciated.