In article , BigWallop
writes

"kitchenman" wrote in message
...
The non return valve is normally on the cold side, so that water from the
tank cant get into the mains water.

If the mains fails, water could get into it if both the taps are turned on
&
there is no non return valve.

Better taps have a dual spout & doesn't need this, the water mixes out of
a
closed vessel.


I'm sure I read or was told that all monobloc taps sold in the UK now have
to have the separation system in the swivel spout.

You'd better tell B&Q that cos most of theirs don't.
--
Tim Mitchell