Mark Philburn-Global Correspondent

Q: I have been a frequent visitor to this column for many years and have collected some very good suggestions. My Lasco bathtub/shower unit is leaking (circa 1992). After I recently scrubbed the bathtub, I sucked no more than 2 gallons of water into the bathtub for a final rinse, and then drained it out. The next morning, I noticed a 3 square inch water stain on the ceiling of the half-bathroom below; it was wet and my fingers went through the plasterboard. The stain is directly under the tub drain. Intuitively, I removed the plunger assembly from the drain valve and found that the hollow of the plunger was completely filled with dirty and greasy materials. I cleaned the plunger, reassembled it, and then tested the drain with about 2 gallons of standing water. I often take a bath because there are no obvious signs of water leakage. My drainage situation has improved. I have no reason to believe that the hot and cold input water pipes are leaking or the flanges on the bathtub are not properly sealed. A family member told me that he had encountered the same problem a few years ago (including damage to the drywall). He cleaned the drain valve plunger and has not leaked since. Simple routine cleaning of the plunger can avoid costly pipe repairs, which seems unreasonable. If this is the case, the bathtub should carry these warning labels. Do you think I have solved my problem, or am I still at risk of leakage?

A. Thank you for your in-depth study of the drainage components and clearly solved what I think is part of the problem. I'm glad it worked, but I don't want to say that there is another problem lurking somewhere. If you think about it, the bathtub and the entire drain should be completely waterproof. If the drain is clogged or slow, it should go back into the bathtub rather than into the ceiling below. I think you need to call in a plumber and open that part of the ceiling below the bathtub so that they can see the drain, P-trap and any other connections in the area.

Question: Please tell us what this green tank is? I live in the house of my great-grandparents. This must be very old. Someone wrote "Don't Remove" on it with chalk.

A. The green water tank is the expansion tank of the old hot water heating system. They are usually placed in the attic or on the top floor. I assume that the house has a newer heating system. If so, it should be safe to remove it. However, I will first try to take a peek under the attic slab to check the old pipes tied to the straps or wall panels so that there is no need for plaster repair work after pulling them out.

Mark Philben is the project development manager for Charlie Allen Renovations in Cambridge. Send your questions to [email protected]. The question needs to be edited. Subscribe to our free real estate newsletter at pages.email.bostonglobe.com/AddressSignUp. Follow us @globehomes on Facebook, LinkedIn, Instagram and Twitter.