Double check vs. single check valves

[drood]

I have read that one should install double check valves where there is a chance of foul water being siphoned back into the mains supply, e.g. on a hose outlet or toilet cistern fed from the mains.

I need to install a bath directly from the mains, so does this require a DC valve or would a (single) check valve be sufficient? I am not sure about the difference as regards the law.

Many thanks.

 

[oilman]

As afr as I know baths don't need check valves, but there is a clearance (I think 30mm) between the level of the tap outlet and the level of the rim of the bath. It does mean you shouldn't have a hose type fitting on the tap/tap assembly.

 

[AdamW]

Does that mean that a bath/shower mixer tap can't be attached to the mains? Or do they have a check valve built in?

 

[drood]

Thanks, Oilman - I'm sure we've met somewhere before

I thought this must be the case coz it's unlikely water could ever be siphoned back thru a tap on a bath, unless as you say a hose is fitted, but some of our regs appear a bit ott at times!

Cheers.

 

[fred67]

If it is a mains fed mixer, then according to the water regs check valves should be fitted. If it is a manual type mixer it should be double check, or on auto mixer (ie self dropping) it should be single.