The phone calls usually start around the end of June. After a run of two or three hot, humid days, there will be a couple of messages on my answering machine asking me to come out and fix a leaking toilet. When I arrive, the customer points at the damp bathroom floor and tells me his or her toilet is leaking. More often than not, I discover that the toilet isn't leaking, it's sweating. Condensation (the correct term for what's taking place when a toilet sweats) will form on the outside of a freshly flushed toilet as the cold refill water contacts the room-temperature porcelain surfaces of the toilet. If the customers have difficulty understanding the underlying physics of condensation, I ask them
