I have a 1-gallon cask that I use for oaking small batches. I've used it for
several years, but this year, it sprung a leak.

Before I was ready to use it, I filled it with water and let it sit for four
or five days so that the staves would swell up and be water-tight. After I
was sure that it wasn't leaking, I drained the water and filled with wine. I
checked each morning and evening for a few days and there was no leakage.

After about ten days, I opened the basement door and smelled wine from the
top of the steps. My first thought was that the cat might have knocked a
bottle off the racks but I found that several ounces of wine had leaked out
of the end of the barrel, where the staves are grooved to fit the
barrel-head. I put the wine back into a gallon jug and topped off.

Any ideas of why a barrel would decide to start leaking after more than a
week? Any way to fix it?

Paul