I noticed that there was a leak downstairs from my first floor toilet, i have engaged a few contractors to check and fix and the problem is still not solved. There is no one using the toilet since its a guest room, i only go in to wash the toilet and noticed the leakage.

I have tested to determine if its a tile waterproof or internal piping issue by turning on the stopper (after few weeks of non usage / non cleaning), within a day, there will be leak to the bottom ceiling.

One of the contractor claimed there is a crack in the concrete upon inspection from below, another claimed there is a crack in the drainage hole. A couple of them just don't contact me anymore after inspection despite promising a quotation.

One of the contractor tried waterproofing the floor tiles and still leaking. Another contractor suggested pulling new pipes from the ceiling (no hacking of tiles).

Appreciate any thoughts on this matter, if its a truly internal piping issue or other possibility.

House (and toilet) is newly renovated for about three years.