Check valve on cold to in body mixer tap

[Mgrant]

Hi, does any one fit a check valve on the cold feed to an in-body mixer tap? Heard water regs states you should?

 

[Ric2013]

Also interested in this question as my WRAS book says the water regs say there should be a single check valve on both hot and cold sides if mixing takes place in the tap, even if cold and hot are balanced (i.e. both mains, or both from tank pressure).

The next paragraph says that the Water Supply Industry deems that the requirements of the regulation will be met if mixing takes place in the tap and no valves are fitted, provided both sides are balanced. Which sounds a bit contradictory to me (probably some distinction being made between what the Regs state, and what is actually required?)

If no mixing takes place in the tap body, check valves not required, but doesn't sound like the situation you are describing.