Ok, this is what you do, go to tescos buy bottled water and claim it back of the next bill, tell your neighbours to do the same, (pardon the pun) don't take the piss, but for example you can I assume refill the cistern etc you at least need a wash daily etc, even if it is a sink and flannel wash. You are paying them for a service which qualifies as a basic need. If they refuse to reimburse threaten either small claims court, OFWAT, or mixed media campaign e.g. Facebook, twitter etc. if they still refuse carry your threat out. Plus threaten to switch provider if you can.
If you can fill the unforgiving minute,
With sixty seconds worth of distance run,
Yours is the Earth and everything that's in it,
And - which is more - you'll be a man my son.