Water on ground slab, cause and leak unknown

Hello forum,

the penetrating moisture can only have a few causes:

- Tap water: test with water meter negative, theoretically there could still be a leak before the water meter.

- Backflow of wastewater: wastewater always smells, so probably negative, the pending sewer inspection will bring clarity.

- Heating leak: if the pressure in the heating system remains constant, it is tight. I assume this point has already been considered - negative

- Condensation moisture: the dew point is not undershot - negative

- Faulty roof drainage: the moisture flows evenly in all weather - negative

- Penetrating moisture from the ground: even if the building structure was constructed as a [Weiße Wanne], the tightness is not proven. Penetrating moisture can flow in evenly.

If the sewer inspection brings nothing (which I assume), in my opinion only penetrating moisture from the ground remains. Otherwise, the even flowing in of the water cannot be explained.

The cause is therefore probably somewhere in the building structure, or in the area of earth-contacting wall penetrations (electricity, water, wastewater pipes, etc.).

A leaking wall penetration can be repaired quite easily after precise localization.

In case of defects in the building structure itself, you will probably face an extensive renovation.

Good luck and best regards

Kristof

Did you have a soil survey done before construction started back then? What did it say? For the examination of samples of any kind: institutes very well know what to analyze the sample for if they are informed of the problem. Possibly send comparison samples as well, e.g. tap water, rainwater, soil sample, to possibly rule out.

Prefabricated wall elements do not automatically mean a white tank either. The shell builder is conveniently bankrupt and the house was self-built, there was water in the excavation pit ... a certain suspicion arises. Soil survey - I think you can probably guess the answer given the situation.

So, I'm getting back in touch after several examinations have been carried out. I invited a friend to inspect the sewage pipes with a camera -> everything was sealed and without problems. He told me to notify my building insurance and act accordingly. I did so and was asked to commission a leak detection company. The company arrived the next day. First, the specialist shut off the main water line for about 1 minute. Then he immediately turned it back on. At first, you could see the little wheel turning until it stopped again. This means that the pipe with the leak initially released pressure and then, after reopening the line, water flowed back in. We then went into the apartment in the basement. As if he knew, the man went to the kitchen and checked the water pipes under the sink, and sure enough, the water supply to the washing machine had a leak. It wasn’t tightened properly, so water ran down the pipe onto the floor slab. The reason the water meter didn’t turn, the specialist explained, is that these meters only turn starting from 10 liters per hour. Afterwards, just to be safe, a pressure test was done on the pipes—everything sealed. The water connection was tightened and the problem resolved. After the leak detection, my insurance asked me to order the drying. Which I did immediately. Possibly, the tenant’s liability insurance will be held accountable, as he is the cause. Thanks again to everyone for the support and help.

Thank you for the report.

As so often in life, after much guessing and increasingly complex thought processes, the most banal solution comes up...

However, I don't quite understand the thing with the water meter and the indication in L/min. Doesn't it show the total consumption?

If it had only moved a little after a night when no one went to the bathroom, wouldn't a pipe problem have immediately been obvious?

However, I don't quite understand the thing with the water meter and the indication in L/min. Doesn't it show the total consumption?

No, water meters are not calibrated for very small quantities. Unfortunately, I don't know exactly which flow rate must be exceeded for the meter to register. I only know from aquaristics that aquarium water is continuously refilled "drop by drop" so that the water meter does not register.