I live in NYC and have a bathtub which when I fill with water and then release the drained water then it leaks into the apartment below me. If I take a normal shower then it is fine. What is this related with and is it cheap to fix it?
Another question is I live in NYC co-op apartment. Is it my responsibility or the co-ops responsibility in this case.

This may be nothing more then a bad drain seal. Let's check and see. Close the stopper to the tub and fill the tub with a few inches of water. Let it set for awhile and check with the apartment downstairs for moisture. If yes then you have a ruptured drain seal and nit can be repaired without opening up the ceiling below. If no moisture moisture appears then let the water drain out and keep checking for moisture. If you see any then you have a leak in the trap area and the ceiling will have to be opened up.

Another question is I live in NYC co-op apartment. Is it my responsibility or the co-ops responsibility in this case
Since this is not considered to be a "common area" the expense will ne on you. Good luck and let me know what you find and we'll go for a repair. Tom

Thanks speedball1 for the quick reply. I did that and in both the cases I could not feel any moisture. I filled the tub waited for about 10 min and went downstairs. No moisture. I then let it drain waited for 10 minutes. No moisture. Should I wait for a longer period. I have told access to their apartment tomorrow and day after. Any suggestions.

When you filled the tub how much water did you put in it? How much water do you use when you bathe?
Let me know. Tom

I put around 12-15 inches of water. I normally have that much water when I bathe. I tried several times now but seems that the problem has mysteriously disappeared. I rarely take bath (probably once or twice a year or so), take only showers.

So can I ignore this problem for now or should I show it to some plumber because it could get worse.

If you normally put that much water in it may be that the leak is from the overflow. When you're not knocking the water around maybe the water is not exiting from the overflow. I had the same problem and only realized the overflow gasket was bad when I opened the wall and could see light through the overflow opening.

Thanks

So can I ignore this problem for now or should I show it to some plumber because it could get worse. Show what? A drain that's working? A plumber can do nothing until there's a problem.
Live with it! Watch it! And if it starts to leak again then pinpoint the leak and we'll fix it. Good luck, tom