What should I do if I keep pouring water from upstairs to downstairs?

If you know who did it, don't go to him or warn him. Be as kind to him as possible. When you see a smiling person say hello in the morning, you can care about his family, don't let him feel defensive, and then focus on it. You can take action after waiting for some time. I suggest you fill a can of feces first and dump it at their door at two in the middle of the night. There will be surprises in the morning. Hearing their shouts will make you feel very relieved. Then he opened the door and smiled and said to him, Good morning, what happened?

Hope to adopt, I wish you a happy life!