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