No.1 U.K. Professional Trade Forum, Plumbing, Gas, Electric, Tiling and Joinery Forum

I am wondering if an outside tap is installed without built in check valves, is an existing double check valve above the main stopcock good enough, - or must the supply pipe to the tap have a check valve?

My thinking is the existing check valve will prevent back siphonage into the underground mains supply.
And a back siphonage to the house mains taps etc, is highly unlikely unless a garden hose was to be above the height of house taps.
But I guess “highly unlikely” does not prevent regs

is it not the location so the back flow cant enter the circulating supply?
i.e. after it 't's to o/s tap?

DC on bib tap

REDSAW wrote: ↑

September 27th, 2018, 1:34 pm

is it not the location so the back flow cant enter the circulating supply?
i.e. after it 't's to o/s tap?

DC on bib tap

Yes, I guess there is no other way around the regs other than to have a DC on the pipe to tap, or use a DC tap, which I avoid because of frost damage risk to the valve inside tap.
Job I was thinking of could never have back siphonage unless the customer put the end of hose into something very high up, but regs are regs.

Best wrote: ↑

September 27th, 2018, 2:40 pm

REDSAW wrote: ↑

September 27th, 2018, 1:34 pm

is it not the location so the back flow cant enter the circulating supply?
i.e. after it 't's to o/s tap?

DC on bib tap

Yes, I guess there is no other way around the regs other than to have a DC on the pipe to tap, or use a DC tap, which I avoid because of frost damage risk to the valve inside tap.
Job I was thinking of could never have back siphonage unless the customer put the end of hose into something very high up, but regs are regs.

just stick dcv on cok, tell sustomer to turn off in winter and cover up. if they dont and it jams easy money in spring

I did a new outside tap install and put a full flow Peglers lever valve on the pipe to the tap and advised customer to turn it off in winter.

Water board are only worried about back flow getting into their mains and not your house.

kozak1968 wrote: ↑

March 17th, 2019, 4:51 pm

Water board are only worried about back flow getting into their mains and not your house.

where as building regs will have you over a barrel if they could be rsed, over a trivial matter like this.

Before I bury the well-to-house line Id like to tap a line of to feed a hydrant in the garden thats about 40/50 feet away from that line. Should I put a check valve in that tap? If so, where would it be best to locate it? Near the hydrant or near the main line?

NikIncawn wrote: ↑

May 26th, 2019, 3:07 am

Before I bury the well-to-house line Id like to tap a line of to feed a hydrant in the garden thats about 40/50 feet away from that line. Should I put a check valve in that tap? If so, where would it be best to locate it? Near the hydrant or near the main line?

best of, near or at the hydrant so its maintainable.

"just stick dcv on cok, tell customers to turn off in winter and cover-up. if they don't and it jams easy money in spring "

Good one
But hey, this is a solution. You can tell the customer that this problem would occur and I'm sure they'd be glad to follow through it.