New Blue MDPE mains water supply and outbuilding supply

[brewhut]

Hi

My next door neighbour recently replaced his mains water pipe. United Utilities let him dig his own trench and lay blue MDPE 25mm polypipe. As long as their spec was adhered to, i.e trench depth….. etc etc….

I want to do the same and replace the old pipe in the front garden. I read somewhere that you need a stopcock and drain valve as a first stage as the pipe comes into the house. I would like to extend a water supply to my shed/garage building in the back garden which is about 40m away from where the main enters the house. I could run it from the mains input to the back of the house, underneath the floor then in a trench starting in the back garden.

I’ve drawn the following diagram, but not being a plumber, I’m not sure if this is the best way of doing it. Ideally I would like to keep the pressure as high as possible for the garden supply. The house only has 15mm leading to system.

1. What’s the best way to do this ?
2. Do I need a NRV as indicated on diagram ?
3. Does UT need to be told about doing the back garden feed ?
4. Would UT need to ok the back garden feed, trenches etc as per the front garden ?
5. The back might be installed separately after the new front house mains, is this ok ?

Any help with this much appreciated, thanks in advance

 

[JimCrow]

The DCV should be immediately after the stopcock and before the drain cock

View media item 58680 [/img]

 

[Charnwood]

Is there a reason for not teeing off the MDPE underground and fitting a stopcock and a DCV in a chamber?

 

[brewhut]

Hi

Thanks for your replies.

I’ve not contacted UT yet, thought I’d come on here first and get some info and ideas, so I know what I’m talking about when I speak to them.

Not being a plumber I had to look up DCV, now I know.
Jim, can’t see the image you posted, why does that need to be there and why double, not single ?
Will this slow the flow of a nice 25mm pipe ?

Charnwood, I did think about teeing the blue pipe under the floor boards, but the UT doc says first connection must be stopcock, which would be above the floor in cupboard. Also if the joint leaked, I might never know till the house floods and lastly, I wanted to be able to isolate the garden supply.

The United Utilities document LCSP19 “How to lay a new water supply pipe” has 8 steps to follow. In step 7 it says:-

“7 Fitting a stop tap at the point of entry to a building: A suitable stop tap (BS 1010) and drain off valve (BS2879) must be fitted, as soon as the pipe enters the building. This must be as close to the point where the pipe enters the building as is possible.”

No mention of a DCV or NRV, I read somewhere that a good stopcock does it. I only added that NRV because of contamination from the garden supply, hence that point in the diagram where I thought it would be.

Thanks for help so far, but does anyone have any answers to my original questions ?

Somebody must have done or require a similar solution to this.

Cheers

 

[Agile]

Any garden outlet should have a NRV to an open tap and probably a double NRV if supplying a hose pipe ( although this is rarely done ).

Tony

 

[mogget]

No mention of a DCV or NRV, I read somewhere that a good stopcock does it. I only added that NRV because of contamination from the garden supply, hence that point in the diagram where I thought it would be.

I had a separation of supply done a few years ago under the lead replacement scheme (Wessex water).

I fitted a stop tap, double check valve and drain cock. When the water company came round to inspect and connect, they said that there was no need for a double check valve on the incoming main.

So I would have thought that the OP's suggestion of where the double check valve should go would be the correct solution.

I'm quite prepared to be corrected myself though, if anyone knows better, or indeed if the regs have changed in the last few years.

 

[brewhut]

There will be a cold tap with a sink in the building for my homebrew.

So does this DCV or NRV need connecting as per the diagram (after the tee) or can it be connected in the garden building, I’ll probably have another stopcock in there anyway

I might use a full bore valve for garden supply

UT need to ok the work for installing the mdpe pipe from their mains in front garden to cupboard with stopcock and drain valve in the house. If I tee off the supply (as in diagram) do they have to be informed, or can I just do the work myself later

Does the work (trench depth etc….) have to comply with them, like the mains supply

I found this below on the internet, items 1, 2, 3 and 4(I)

Notification
In most cases, before work starts on any proposed plumbing installation, the installer, owner or occupier must give notice that he proposes to begin work. If you need a notification form (WRN20-1) please contact us. The plumbing work for which notification must be submitted is shown in the following table:

The installation of a water fitting in connection with:
1 The erection of a building or structure, not being a pond or swimming pool
2 The extension or alteration of a water system on any premises other
than a house
3 A material change of use of the premises
4 The installation of:
4 (a) A bath having a capacity as measured to the centre line of the overflow,
of more than 230 litres.
4 (b) A bidet with an ascending spray or flexible hose.
4 (c) A single shower unit that may consist of one or more shower heads within
a single unit of a type specified by the Regulator
4 (d) A pump or booster drawing more than 12 litres per min, connected
directly/indirectly to a supply pipe
4 (e) A unit which incorporates a reverse osmosis
4 (f) A water treatment unit which produces a waste water discharge or which
requires the use of water for regeneration or cleaning.
4 (g) A Reduced Pressure Zone (RPZ) valve assembly or other mechanical device
for protection against a fluid which is in fluid Category 4 or 5
4 (h) A garden watering system, unless designed to be operated by hand
4 (I) Any water laid outside a building and either less than 750mm below ground
level or more than 1350mm below ground level.
5 The construction of a pond or swimming pool with a capacity greater than
10,000 litres, which is designed to be replenished by automatic means with
water supplied by the statutory water supplier.

 

[bolshy]

OP, your idea is sound. You don't need a double check valve on the supply to your house. It is fitted to stop backflow from any contaminated water in the garden, in case of back siphonage caused by mains pressure loss. The requirements for a garden tap outlet or the like (because it can be connected to a perforated hose, sprinkler, etc) is an isolation valve, double check valve and then outlet. If the ONLY outlet on the pipe to the shed is the one in the shed, then the double check valve can be fitted there.
However, it is strongly advised to fit the DCV indoors above floor level where possible though, they are prone to freezing.
Put your 22mm isolator just after the tee branch, and your 22mm DCV where you were going to put your 22mm isolator. Any gardens outlets downstream will then comply.

 

[brewhut]

Thanks for that Bolshy that helps a lot, would I still have to use a stopcock after the tee or can I use a full bore level valve

just phoned UU, asked if they need to inspect blue pipe in trench etc, not much help when I mentioned wanting to run feed to shed , they said talk to a WIAPS plumber, might have to contact one to find out how much work I can do (digging etc) to keep the cost down.

Does anyone know any ok plumbers in Manchester area

 

[bolshy]

I'd put a 22mm stop cock in, it complies with the regs then. The only bit of your new pipework they need to see is the incoming main. Adding a run of mdpe to the shed after your new incoming main stop tap has nothing to do with UU, they won't be interested.
But to protect your drinking water, and your investment (against mechanical and frost damage) stick with the regulations. If you're going to dig a trench, get a mini-digger with driver, shouldn't cost more than 250 quid for the day, he can dig both trenches. Be careful not to damage any other services to the house.
Alternatively, you can do as much of the digging yourself as you like on your own property. Believe me though, it'll take a long time to do it by hand, especially if you hit clay.
I'm a WIAPS plumber, if you provide the main materials, I'm sure we could get this done in a day, if the trenches are done. I quite enjoy laying the odd mdpe main once in a while. You're only an hour's drive away. Then you just have to wait for UU to connect.
PM me if you're struggling.