Non return (check) valve for garden water

[Bitpipe]

When we built the house we ran new MPDE to the existing (fairly new) stopcock.

 

There was an existing run of MPDE to garden taps so the contractor tee'd off the main to connect to these (must be about 10m of MPDE between the tee and the first tap. I don't believe he put in a non return valve when making these connections, there wasn't one there before from the old property, just a cast iron main to the boundary which teed off to house and garden.

 

We're doing final landscaping at the front and need to plant some new hedging as a planning condition, together with irrigation system.

 

Contractor will need to uncover the new MPDE run to the house and tee off that - does he need to add a check valve to that?

 

If so, is it worth adding one for the other tee for the garden taps also?

[Onoff]

I believe you need a check valve on garden taps to stop back syphoning but why not just change the taps for ones with built in check valves?

[ProDave]

Yes you do need a double check valve, In my case it was checked by Scottish water before they would authorise a connection.

 

To save digging it up, my check valve is just in line with the bit of pipe that runs up the post, above ground level, and then insulated as best I can.

[Temp]

https://www.screwfix.com/p/outside-tap-with-double-check-valve-15mm-x-mm/37241

 

 

[Onoff]

14 minutes ago, Temp said:

https://www.screwfix.com/p/outside-tap-with-double-check-valve-15mm-x-mm/37241

 

 

 

Fitted the exact same one. Stainless steel screws and all nice and dead level too:

 

 

Followed the @Nickfromwalesmethod winding circa 25 turns of PTFE tape on before screwing the tap into the boss and stopping when it "felt right". Job done.

 

(And yes I've painted over the brown EBT now )

Edited November 16, 2017 by Onoff

[Nickfromwales]

Tres bien Rodney ?

[ProDave]

I have a tap like that on my standpipe. SW would not accept it, it had to be a separate non return valve.

 

Have I ever mentioned there is a NRV in SW's toby. Then a NRV in my own toby. Then the in line NRV. Then the NRV in the tap.

 

I suspect no water will ever flow backwards

[Nickfromwales]

3 hours ago, Bitpipe said:

When we built the house we ran new MPDE to the existing (fairly new) stopcock.

 

There was an existing run of MPDE to garden taps so the contractor tee'd off the main to connect to these (must be about 10m of MPDE between the tee and the first tap. I don't believe he put in a non return valve when making these connections, there wasn't one there before from the old property, just a cast iron main to the boundary which teed off to house and garden.

 

We're doing final landscaping at the front and need to plant some new hedging as a planning condition, together with irrigation system.

 

Contractor will need to uncover the new MPDE run to the house and tee off that - does he need to add a check valve to that?

 

If so, is it worth adding one for the other tee for the garden taps also?

You only fit NRV's above ground, so basically anywhere where the incoming cold main rises above ground you should have a stopcock and a NRV directly after. Relying on the one in the tap isn't the best measure TBH as in most instances the outside tap is already covered by the house arrangement, ascits fed from the domestic supply not the main.  

You should have a stopcock, and double check NRV whenever connecting independently to the main . 

[Onoff]

9 minutes ago, Nickfromwales said:

Tres bien Rodney ?

 

What was that number of turns...23 - 29 you said? I remember thinking it was excessive at the time having always done far less (and having thd odd leak and the tap turning) Tentatively did it and once again thought "Smart ar** plumbing guru!" My goto method now!

[Mr Punter]

Our local BM no longer stocks the taps with the built in check valves as he reckoned they were prone to splitting when / if they froze.  We just put the check valve inside the building.

[Nickfromwales]

10 minutes ago, Onoff said:

 

What was that number of turns...23 - 29 you said? I remember thinking it was excessive at the time having always done far less (and having thd odd leak and the tap turning) Tentatively did it and once again thought "Smart ar** plumbing guru!" My goto method now!

25-29/30 turns is fine, and the tap will just displace what it doesn't want leaving a 'collar' of tape between the two mating surfaces.  Quick whip round with a stanly or junior hacksaw and clean off the excess on show and it's job done. 

 

6 minutes ago, Mr Punter said:

Our local BM no longer stocks the taps with the built in check valves as he reckoned they were prone to splitting when / if they froze.  We just put the check valve inside the building.

Can't say I've seen much of that TBH, but in colder climates it makes perfect sense as the slug of water trapped between the tap and the NRV has nowhere to go. 

Best solution is 1) isolation 2) nrv 3) tap. 

Isolation and nrv inside of possible and when the frost hits just open the tap and close the isolation to prevent bursts. 

[ProDave]

Mine has  little bleed screw on the bottom to empty the water stuck in the NRV bit.

[Nickfromwales]

1 minute ago, ProDave said:

Mine has  little bleed screw on the bottom to empty the water stuck in the NRV bit.

They ( the non return ones ) all have that but it's not meant for routine use. Iirc it's for service / maintenance use.  

[ProDave]

5 minutes ago, Nickfromwales said:

They ( the non return ones ) all have that but it's not meant for routine use. Iirc it's for service / maintenance use.  

Oh.  I undo mine and drain it every winter. Most times in the spring I remember where I put it.

[Nickfromwales]

1 minute ago, ProDave said:

Oh.  I undo mine and drain it every winter. Most times in the spring I remember where I put it.

I think in the blistering heat of the Scottish highlands you'd be best off continuing to do so. Or, retro fit an internal isolation valve like I did ( to stop the kids arsing around ) and change to a regular ourside tap so you can just turn a valve off and leave the tap open seasonally. 

[Onoff]

Just bought a couple of those foam outside tap covers from Screwfix on the back of this thread.

 

https://www.screwfix.com/p/outside-tap-cover-x-19mm-x/77873?kpid=77873&ds_rl=1245250&gclid=EAIaIQobChMIw4bSwejD1wIVCucbCh10_QIyEAQYASABEgL8GvD_BwE&gclsrc=aw.ds&dclid=CLrCrsPow9cCFWmn7QodxaMO5w

[Jeremy Harris]

1 hour ago, Onoff said:

 

Fitted the exact same one. Stainless steel screws and all nice and dead level too:

 

 

Followed the @Nickfromwalesmethod winding circa 25 turns of PTFE tape on before screwing the tap into the boss and stopping when it "felt right". Job done.

 

(And yes I've painted over the brown EBT now )

 

 

As a tip from someone with three of the same taps, replace the cross head centre screw with a brass one.  The brass coloured one in there is brass plated crap steel and will rust like an anchor inside 6 months.  IIRC, a standard brass countersunk M4 screw fits a treat.

[Onoff]

8 minutes ago, JSHarris said:

 

 

As a tip from someone with three of the same taps, replace the cross head centre screw with a brass one.  The brass coloured one in there is brass plated crap steel and will rust like an anchor inside 6 months.  IIRC, a standard brass countersunk M4 screw fits a treat.

 

Sounds like a job for an M4 conduit lid screw and I've got loads of them. Cheers.

[Nickfromwales]

5 hours ago, JSHarris said:

 

 

As a tip from someone with three of the same taps, replace the cross head centre screw with a brass one.  The brass coloured one in there is brass plated crap steel and will rust like an anchor inside 6 months.  IIRC, a standard brass countersunk M4 screw fits a treat.

Yup. Total and utter madness. They rust out in weeks, just crazy that it's not brass also.

Good point ?

[Bitpipe]

15 hours ago, Nickfromwales said:

You only fit NRV's above ground, so basically anywhere where the incoming cold main rises above ground you should have a stopcock and a NRV directly after. Relying on the one in the tap isn't the best measure TBH as in most instances the outside tap is already covered by the house arrangement, ascits fed from the domestic supply not the main.  

You should have a stopcock, and double check NRV whenever connecting independently to the main . 

 

So there should be one in our plumbing arrangement as the main enters the house (will check with plumber) and sounds like I just need to replace all the old taps in the garden plus use one on the new irrigation system.

 

Cheers!

[Nickfromwales]

1 hour ago, Bitpipe said:

 

So there should be one in our plumbing arrangement as the main enters the house (will check with plumber) and sounds like I just need to replace all the old taps in the garden plus use one on the new irrigation system.

 

Cheers!

Basically just preventing back flow into the main is the criteria, howsoever achieved. 

After the domestic stopcock you don't need anything really as far as water bylaws / regs are involved / concerned, but it's better to have non returns on. or immediately prior to, the outside taps so draining down inside the house can never syphon dirty water back from a connected outdoor pipe / hose into the potable network. 

Again, anywhere where the MAIN rises needs the bylaw adhering to, and a non return outside tap does not tick that box .  

[Bitpipe]

38 minutes ago, Nickfromwales said:

Basically just preventing back flow into the main is the criteria, howsoever achieved. 

After the domestic stopcock you don't need anything really as far as water bylaws / regs are involved / concerned, but it's better to have non returns on. or immediately prior to, the outside taps so draining down inside the house can never syphon dirty water back from a connected outdoor pipe / hose into the potable network. 

Again, anywhere where the MAIN rises needs the bylaw adhering to, and a non return outside tap does not tick that box .  

 

The stopcock is fairly recent (last 10 years) so would it have a NRV built in? When we replaced the our side of the main, the old cast iron pipe ran straight into it.

 

Anyway, just realised that the supply that we ran to the caravan (25mm MDPE) which is still live and has been coiled up (potential additional outside tap) could now be dug out and re-run to where we need the irrigation, saving trying to find the main again!

[Nickfromwales]

Most stopcocks don't fill the requirement, even brass ones which are supposed to fall back and seal themselves ( only really effective under forced back flow imo ) so that's why all water authorities ask for a stand alone NRV immediately after the stopcock on the rising main. 

If your coil of mdpe is teed off the underground main supply then you should fit a stopcock and a double check NRV immediately after it breaks ground. After that you can do what you like. 

[Jeremy Harris]

18 minutes ago, Nickfromwales said:

Most stopcocks don't fill the requirement, even brass ones which are supposed to fall back and seal themselves ( only really effective under forced back flow imo ) so that's why all water authorities ask for a stand alone NRV immediately after the stopcock on the rising main. 

If your coil of mdpe is teed off the underground main supply then you should fit a stopcock and a double check NRV immediately after it breaks ground. After that you can do what you like. 

 

I agree 100%.  Every single one of these I've taken apart over the years has had the "floating" piston rod stuck firmly in the bore of the shaft, so that it just moves up and down as the handle is turned.  My personal view is that the reason that the water companies became so insistent on having proper double NRVs in recent times is that they know full well that the backflow prevention built-in to a stopcock usually doesn't work................

[Nickfromwales]

Plus every mdpe stopcock I've ever seen has had no such internal nrv.