Isn't the water company supposed to give you
some kind of legal notice before they shut your
water off? I know I've received that sort of
notice in the mail before. They notify you that
they haven't received your payment, and that
your service will be shut off on such and such
a date if they haven't been paid by then.

Of course those notices also say to ignore
them if you've already sent payment, so
perhaps you did get one of those and ignored
it because you remembered mailing out your
check...