Water supply pipe...

[Mike Hibbert]

Hi all,

We are in the process of getting Severn Trent to re-lay our service pipe as the current lead one is leaking (see previous threads).

The existing one goes under the floor in the kitchen, but I dont't want to move all the cupboards out and have the floor up, so I want to use plastic pipe under the cupboard and then join onto the copper under the sink. The other end of the plastic would need to join onto the new supply in the garage - also plastic.

ST say they will "most likely" use 15mm pipe, will that be the inside bore or the diameter of the pipe? I guess it would make sense to use 15mm in the house and use a converter to join onto the copper.

Does this sound like a reasonable plan? Should I use a different diameter plastic onto the copper in the house?

cheers Mike

[G&M]

15mm is far to small. Ask for 22 or 25mm.

[sparky]

Normal size for the supply pipe in a domestic new property these days is

[Kalico]

15 mm will not be sufficient. It may mean a little more mess but the pipe should be MDPE of at least 25mm to accommodate modern water usage in an average house. After the stop-tap, it is ok to take it down to 22mm or 15mm to connect to the existing system.

Actually, I am suprised that ST say they might use 15mm pipe since I was not aware that MDPE pipe existed in that size.

Just out of interest, are they offering to do the work for free?

Rob

[Witchy]

I don't understand this - if it's OK for it to be stepped down to 15mm inside the house how can a 15mm pipe outside the house to the water main not be sufficient? Is it something to do with flow and pressure or am I being friday morning thick? :)

-- cheers,

witchy/binarydinosaurs

[BigWallop]

If the mains water supply was only 15mm diameter pipe, you probably wouldn't get the flow rate you needed to fill the washing machine and run a tap at the same time. I know when we first moved in here the shower, the kitchen cold tap and the washing machine were all off a 15mm pipe, and it played havoc when you wanted a nice hot shower and someone turned the tap or the machine on. All separated now from a 22mm pipe and they work fine together.

[fred]

Resistance to flow depends on the length at a given diameter so a 10m run of

25mm MDPE + 5m of 15mm copper has less resistance to flow than a 15m run of 15mm.

Quick (cerial packet) calc shows the all 15mm case has 50% more restriction to flow than the mixed case.

That said, I wouldn't run all the cold stuff in my house off a single 15mm . . . .

So the message is, the longer your front garden, the thicker the feed pipe you need.

[Mike Hibbert]

Doh! Ther are actually using 25mm pipe, i called them today and checked.

They are making a charge for it, they don't do things for free! It is £500

• vat, whcih isn't too bad I guess.

>

[Dave Liquorice]

I guess not but all the same did you miss my comment about some water boards replacing lead service pipes for free if there was no lead in the house anymore?

[Ed Sirett]

The ID of the 20mm MDPE blue pipe and 15mm copper are about the same namely 1/2".

25mm blue poly is the norm for new build which converts to the 22mm inside.

[Mike Hibbert]

I guess not but all the same did you miss my comment about some water boards replacing lead service pipes for free if there was no lead in the house anymore?

No, not at all, that was one of the main reasons for calling ST in the first place. They won't replace for free, but they said that if I replace my service pipe, they will upgrade the pipe from the boundary to the main pipe in the road for free (if it needs doing). They also have paid £150 towards the cost.

Cheers for your advice!

Mike

[Witchy]

I'm allowed to be thick on friday mornings :o)

All the 'wet area' of our house is contained on one wall at the back so we're fine with the 25mm MDPE that we had put in a couple of years back. It explains why we could then have at least 2 taps on at the same time whereas with the 36m run of lead pipe up the back yard that was in use before we were lucky to have 1 tap!

-- cheers,

witchy/binarydinosaurs

[Dave Liquorice]

That would be good here, the external stopcock is about 25yds down the road from our boundary. But we are already on plastic, mains water is fairly new to this house, probably less than 20 years.

Better than a kick in the teeth. B-)

[Nick Brooks]

I think the water company are OBLIGED to provide a water main to the edge of your property. You are then liable for any costs to get it into the house. You also have to meet their requirements regarding depth and type of pipe.

They supply 25 MDPE and you can buy a stop valve which takes this on one side and has a 22mm compression fitting on the other

Nick

Dave Liquorice wrote:

[Dave Liquorice]

Doesn't help our nearest neighbour, the 63mm main actually passes round the back of our house through his land. Unfortunately his house is 1/2 mile away and a good 300' lower. The head here is about 150' so a 450' would be a tad exccesive... Needless to say they have their own water supply.