It is likely that the drain pipe leaks;
First drain the water from the faucet at home, find a hose with one end facing the faucet upstairs and the other end facing the floor drain upstairs, and stick to it for half an hour (don't let the water flow to the ground at this time) to see if there is any water leakage at home. If there is water leakage, there is something wrong with the floor drain and drain pipe;
If it is confirmed that it is a pipe problem, you can only shave your head;
After testing, either the pipeline problem or the waterproof layer upstairs is broken and leaking, which is very easy to solve;
Welcome to consult Jingfu Building at any time. I'm glad to help you solve this problem.