Water Regulations - Spray tap in Kitchen

[jrees970]

Hi - My wife would like to install a mixer tap for the utility room sink which has a flexible pull-out spray head. My concern is that this then runs into problems with backflow protection, as the spray head can be below sink overflow level.

The tap is currently supplied direct from the rising main (it's a bungalow) - am I right in reading the 1999 water regs that there is no way of providing backflow prevention via Double Check valve in this situation as kitchen sinks count as class 5 ?

Any way round this ?