Mains water leak into solid floor

[markwidgery]

I had a ground floor extension completed about 6 months ago. 3 months ago we noticed what looked like rising damp on some of the internal walls - paint peeling and moisture on the exposed plasterwork. The builder assured it me it was just retained water in the blockwork (the building work was done last January, the wettest on record).

Yesterday I heard the whistling of water running in a pipe in the kitchen late in the evening when everything was off in the house. There is a branch off the rising main that goes back under the floor in the kitchen and supplies the new downstairs bathroom. Closing off the isolating valve on that branch stopped the noise. I turned the valve back on and went to check the water meter (which was installed during the build and I hadn't yet looked at). It is currently reading 913551 (913 in white, 551 in red). As I understand it, in 6 months since installing that meter I have used 913 cubic metres of water. With everything turned off in the house it was still ticking over rapidly and rose by 263 in 30 minutes. I have tested it for 30 mins with this valve closed and there is a very small change in the meter.

As far as I can tell for some months now about 500L/hr, a total of more than 800 cubic meters, of water has been dumped from my internal plumbing into the solid floor. I assume it has tracked along the damp-proof course and is coming out on the internal walls.

The floors were liquid screed laid over the oversite which was over a thick layer of celotex. The living room adjacent to the kitchen has underfloor heating with some extra insulation on top of the oversite. Amazingly considering the volume that has gone in none of the carpets are wet and the laminate floor in the living room is not distorted.

The builder is round tomorrow with the plumber to try to find the leak but mainly I would like advice about the damp. I am also going to get in touch with my insurance company

- what is the effect on a solid floor of having this much water dumped into it?
- will the underfloor insulation ever get dry?
- does the floor need ripping up and re-doing or can we wait for it to dry out?
- if all the moisture is held above the damp-proof membrane will we ever get rid of it
- does anyone have any experience with Thames Water in a situation like this where I am anticipating an astronomical water bill?

Any advice would be much appreciated. Thanks

 

[mcmoby69]

913 cubic m of water?

do you have a swimming pool?

 

[GoodDIYjob]

I think you may get better responses to your floor / sub floor insulation / damage from the building sections of the forum.

Perhaps ask for it to be moved edit it and create a separate one on your water usage in plumbing. Or vice versa.

That is an enormous continuous flow of water. Your indicated leakage in 30min is almost our family of three daily usage!

Are you 100% sure the meter was installed at zero and not installed already showing a reading? Noting your leakage calculation, maybe it was at zero as the 800m3 does seem to correspond roughly to 3 months leakage.

My understanding is thames water are supposed to do readings no more than 6 month intervals. Normally this fits in with a cycle, so often the first cycle when moving into a property is less than 6 months. With a new install the cycle may commence.

Either way you are due a read and a bill now. That usage should flag up to thames water as commercial scale usage and needing customer investigation / contact.

If you, and not the previous owner, have moved to a meter you normally have a right to move back to rateable value but that doesn't solve what will be a significant bill.

At my unit prices your 800m3 is going to be close to £1700.

The problem is clearly on your side of the network but as you have been in ignorance to the water usage, I would be hopeful you could get them to see reason and cancel the excess usage. If they really won't budge, after getting through to the right people, there is an escalation route to independent body ccwater.

I see the guardian take up these causes for readers sometimes as well.

To cut to the chase I think your going to have to contact TW and say you think you've got a problem.

It certainly hasn't helped limit the damage that the builder fobbed you off 3 months ago!! You may want to be selective around how long ago the problem appeared. Edit: or was visible to you. If the builder has been negligent, then maybe he pays or shares costs assuming the worst case outcome.

http://www.theguardian.com/money/2013/jun/17/thames-water-meter-rising-bill

http://www.thameswater.co.uk/help-and-advice/9525.htm

 

[Effluentman]

A 500 litres per hour leak would be flooding your home if it was above ground. It is a kitchen sink cracked open quite some way, so its not a pin hole leak.
That leak must be saturating below ground and the water is rising up through walls and floors where it can.
Was the branch to the new downstairs toilet a new pipe run or re-using an old supply?
If it is a re-use then what used to be fed from this and how was it disconnected?
If it is a new branch then the builder is responsible for the work and any damage liability unless you have subsequently had further work done on it.
The leak is undoubtedly on that branch from your investigation.