The water heaters broke.

Downstairs lost theirs first, ours went a few days after. Ours was fixable, theirs wasn't, and after carefully studying the price of a new water heater I've worked out what happened. Water heaters vary in price according to how long they're expected to last, and my mother bought what she could afford.

This, of course, costs us more in the long run, but guess what we are going to do this year too?

Oh well. Now that I know, we can put money aside for the next time.