Help have a water leak but can’t find the source.

[WaterLeak]

I have a leak which is proving difficult to locate, anyone one with any experience of this willing to help try and locate it please?

The leak is on the ground floor and only happens during or after heavy rain, it is not the roof or soil stack they have been ruled out. There is no evidence of water anywhere upstairs, no damp, no wet patches nothing.

It seems to be originating in the middle of the house in the hallway and then spreading, the floor is absolutely soaked, it’s not a little bit of water.

The central heating system was ruled out yesterday by using dye, even though we use the heating when it’s not raining and the issue only happens in heavy rain.

Housing are coming back today and if they can’t locate it are saying to go ahead and replace the flooring, which I’m not happy with as it will just get ruined again as this has happened four times in the last few weeks. It’s a new build house (2017) with concrete floors and I have no idea what’s underneath it.

This will sound bonkers but is there any chance it’s coming in through your letterbox and then pooling in the middle of the floor?

Before we replaced the letterbox in our new house, it used to leak in water during very heavy rain (Scotland, so quite often 😆)

So it's coming up, from underneath the house?

No can’t see it being the letter box, the hall is 4.5 meters long and the leak seems to be coming from the end of the hall, 4 meters away from the front door.

I can't help you but I sympathise. We have a huge damp patch and rapidly multiplying mould suddenly on our lounge celing. Pipes have been checked and are sound. No one can work out where it's coming from. We are going to have to have the ceiling taken down to find out. Before it falls down I suspect. We have only just moved back in after nearly a year out following a big house fire. At this point I think the house is bloody cursed.

To check for a leak on the water supply pipe coming in from the main in the street turn everything off in the house. Then go out to the meter and see if there's any movement on the dials.
For a sewer leak you will need a camera survey.

Yes I think it’s coming up from through the concrete, housing are saying this is impossible and won’t investigate further.

I have removed flooring in places as it was absolutely soaked, not just a little wet and discovered a 3m hairline crack that runs from the side of the house through the toilet and out into the hallway right to the exact spot I believe the water is coming from.

It's possibly an underground watercourse of some sort that runs under the house then? If natural then rain would cause it to rise and seep up through the floor?

Water follows pipes and any other structures, so even if there's no obvious water upstairs it doesn't mean it isn't a pathway. What makes you think it's not the roof?

If the house was built in 2017 is it still under a 10 year "guarantee" or do they not do that any more?

@junbean because a team of roofers have been out and up on the roof and into the loft and say there is no sign of water damage in the loft or round the soil stack, no missing tiles or flashing. They sprayed the roof with a high pressured hose that was attached to the lorry with a crane they arrived on.

@3dogsandarabbit yes it’s has the 10 year NHBC warranty but I don’t think it’s for things like this and as it’s a HA house not sure I could contact them anyway.