my previous two house got water leaking from upper storey bathroom. the problem is u will only realize it after a few months, or worse it takes years if u didn't use that bathroom frequently. after that experience, I know how to detect it already.

close the drain hole tightly, u can use toilet plunger. then let water become stagnant for a few days in the floor. normally 2-4 inches deep will do. mark the water position, close the door and monitor after few days. if the floor waterproofing not good, after one week u will notice all the water gone and lower storey ceiling will looks wet.

some developer will just paste some waterproofing cream/liquid that will only lasts for a few months. be firm and ask them to hack the floor, do waterproofing again, and tiles it back. monitor using the same method after they finish with the repair. hope this helps.

This post has been edited by xswatch: Sep 25 2020, 01:43 PM