I have a house built about 1990. I noticed some water damage under
the kitchen sink. There seemed to be damp streaks down the p-trap,
so I thought it was the rubber seals. I got a set of o-rings from
hardware store and replaced them. The old rings were hard and leaking,
but later found there was another leak: where the elbow was glued.
So I would like to know - do these glued joints fail after a few
decades? I also have them in the bathroom and laundry.