DIY Doctor UK DIY Forums

I'm preparing to install a new suite in my bathroom and was looking at one of my DIY manuals when I noticed a section which basically said it's illegal to fit a mixer where cold water is supplied from the mains and hot water comes from a cylinder, because if theres a change in mains pressure, stored water might be sucked back into the mains and contaminate drinking supplies.
The suite I'm planning to fit is a European make with monobloc mixer so I'm just wondering if theres a difference between UK and European laws and is this something I need to worry about.

This is indeed true, but the backflow can easily be prevented and with many mixer taps is not possible.

Backflow can easily be prevented by installing a check valve in the cold supply just below the basin tap. Some manufacturers are good enough to supply one with their taps, but this practice is becoming less frequent in a strive to save costs.

The design of some taps prevents the possibility of backflow by keeping the two flows separate right to the spout.

If in doubt, nip to the local merchant and buy a non return valve.