Water leaks in France... who is responsible?
If the leak is after the water meter, it is your responsibility to fix it. Contact a plumber if you are unable to repair the leak yourself. The water company won't compensate you for any damages nor for a huge consumption of water.
If the leak is before the meter, contact the water company straight away (see details on your last water bill). They have a breakdown service so you can contact them 24/7.
Do take photos of any damages.
I have had to deal with several claims due to water damages for my clients so I know the photos are very useful!!