Mains water, DPM and trench in garage

[Jammy5]

Morning all,

 

Firstly I'm learning on the job here and will have made a few mistakes trying to manage the build myself (never again).

 

So, the issue I have is I mistakenly ran 32mm MDPE instead of 25mm for the mains water supply.

 

I also didn't run it at the correct depth as it enters the building (it is under the DPM and 150mm slab in the garage though but definitely not 750mm deep) and didn't insulate it. It enters straight through the garage door opening, so not drilled through the wall.

 

Am I correct that my only option is to install a new mains water pipe?

 

The predicament I find myself in is there isn't alot of remaining space to dig a trench but I'll have to find a way. I intend on running a 100-110mm insulated Flexi pipe for the job with the 25mm internal 

 

Secondly, and the part I need advice on is how can I bring the pipe into the integral garage? Concrete slab is down and DPM laid (I'm at roof truss height). I'll have to disturb the DPM as I create a hole in the garage floor as small as possible but how do I repair the DPM once I have the hole dug/drilled and pipe laid?

 

Also, is it fairly simple to patch the concrete in? Anything specific I need to consider?

 

Any advice on this would be much appreciated.

 

Kind regards,

 

Jamie

[Oz07]

32mm is ok round here although the depth you've got isn't good. Are you thinking of a new trench through the garage slab or just a hole to bring it up? Any sketch?

[Jammy5]

So current thoughts are to dig the front of the garage so the pipe is 750mm and under dig the concrete slab slightly. So the only part that won't be 750mm deep now will be inside the garage.

 

I don't really want to relay the pipe in the garage as it creates an issue in trying to repair the DPM.

 

I'd then have to find a 32/25mm reducer to connect to the boundary box so it's a 25mm connection for the water board as we've been told it must be 25mm (I'm hoping they accept my arguement that the pipe between box and my garage can be larger). 

 

Any thoughts?

[ProDave]

How much do the water company know or want to see?

 

If nothing, just make sure the pipe they are presented with is 25mm and the correct depth.  They don't need to know it then goes to 32mm.  Don't even mention that unless asked.

[Oz07]

Do you not get option for 32mm connection there? Who's your water board? Good idea to come up just inside the garage. If you can tunnel under enough you can get the pipe up through the bottom and just repair dpm with tape and membrane. It's got to be punctured to bring the pipe up through anyway

[Jammy5]

We don't get an option. It's 25mm with United Utilities. 

 

They want to see it at the garage door threshold, so I'd have to fit a reducer under the garage floor and then back fill, which I don't really want to do in case there's a leak? Or is this normal stuff in this day and age?

 

Unfortunately regardless of this, they will then see the 32mm pipe coming up in the garage where they fit the water meter (apparently all water meters are now installed inside the property).

 

So it kind of defeats the object anyways of hiding the fact I'm using 32mm pipe. 

 

I just need to convince them that I can keep the 32mm pipe fit reducers to the connection outside and inside, and then ensure it's installed 750mm down from the garage door for their viewing by digging down.

 

Unless I'm missing anything obvious?

 

Thanks for the replies so far though

 

 

[mjc55]

50 minutes ago, Jammy5 said:

We don't get an option. It's 25mm with United Utilities. 

 

They want to see it at the garage door threshold, so I'd have to fit a reducer under the garage floor and then back fill, which I don't really want to do in case there's a leak? Or is this normal stuff in this day and age?

 

Unfortunately regardless of this, they will then see the 32mm pipe coming up in the garage where they fit the water meter (apparently all water meters are now installed inside the property).

 

So it kind of defeats the object anyways of hiding the fact I'm using 32mm pipe. 

 

I just need to convince them that I can keep the 32mm pipe fit reducers to the connection outside and inside, and then ensure it's installed 750mm down from the garage door for their viewing by digging down.

 

Unless I'm missing anything obvious?

 

Thanks for the replies so far though

 

 

Presumably this is a UU thing.  I thought water meters were generally fitted outside the property boundary.  This was certainly the case for us with Wessex Water.

[Jammy5]

17 minutes ago, mjc55 said:

Presumably this is a UU thing.  I thought water meters were generally fitted outside the property boundary.  This was certainly the case for us with Wessex Water.

https://www.unitedutilities.com/globalassets/documents/pdf/advice-for-builders-and-developers-guidance-booklet.pdf

 

That's the advice document that backs up what they were saying

[dpmiller]

how long is this 32mm run?

[Jammy5]

Say 5m. 1m outside garage, 4m inside garage under slab

Edited 7 hours ago by Jammy5

[mjc55]

11 hours ago, Jammy5 said:

https://www.unitedutilities.com/globalassets/documents/pdf/advice-for-builders-and-developers-guidance-booklet.pdf

 

That's the advice document that backs up what they were saying

That document states that the "The service pipe must be clearly labelled at the boundary with the correct plot number/property number"!  Obviously this is for housing estate but I cant see anywhere that it states that water meter is on your property?

[mjc55]

30 minutes ago, mjc55 said:

That document states that the "The service pipe must be clearly labelled at the boundary with the correct plot number/property number"!  Obviously this is for housing estate but I cant see anywhere that it states that water meter is on your property?

Hmm.  Further reading of that document does seem to indicate that meters are fitted on the property, sorry for the confusion.

[Mr Punter]

Where we are the water company want to inspect the open trench or we record the depth with a tape measure and photos.  On your job they should be able to get the 32mm pipe to work without much trouble.

 

I see that UU will accept a video of the pipework using their app and they have a proposed arrangement for shallow entry pipework.  Depending on the layout, you may have to abandon the existing pipe and start again.  Can you have the meter near to an outside wall?

[Jammy5]

2 hours ago, Mr Punter said:

Where we are the water company want to inspect the open trench or we record the depth with a tape measure and photos.  On your job they should be able to get the 32mm pipe to work without much trouble.

 

I see that UU will accept a video of the pipework using their app and they have a proposed arrangement for shallow entry pipework.  Depending on the layout, you may have to abandon the existing pipe and start again.  Can you have the meter near to an outside wall?

I'm planning on complying with the entry level at 750mm deep crossing the threshold of the garage. Hopefully this is acceptable. 

 

Most of the entry pipework and pipe details assumes you're going through a wall. I'm going through a wide opening below the garage door.

 

Sorry, when you ask can I have a water meter next to an outside wall what were you thinking? I can but I wouldn't be able to dig the trench between the two properties as it already has rainwater/soil pipes running in this compact space and the water pipe would need to be below them and slightly to the side. I'll also need to be in this area for the electricity and fibre connections.

 

Many thanks,

 

Jamie

 

 

[Mr Punter]

Normally you would have the meter and stopcock near to where it enters the property but I don't know the layout for yours.  UU are keen that the pipe does not freeze, hence the 750mm depth.

[saveasteading]

the reason for the pipe being at that depth is to be clear of frost and of excavation/ other physical damage.

 

that doesn't seem to be a risk in your situation, but you must decide on that.

a short length that is not as deep as the standard isn't going to freeze.

 

whether the logic will interest your water people is another matter though, so there is a lot to be said for showing them what they want to see.

 

 

[Jammy5]

Thanks all, will give it a whirl and see how I get on 👍🏼