There is an old well on some communual ground which, according to the
deeds, etc. I (and my neighbours) have to keep maintained and in good
order...

Right now, it looks like it's concreted over with a drain cover. (If
this is where it actually is - we're not 100% sure, and its location
isn't mentioned with any exactness on any of the plans we have)

So assuming I were to open it up again, and the water was of drinkable
quality (or required minimal filtration), am I right in thinking that
I can simply tell the water board where to put their water bills if I
move over to using it?

It is a short way from my house, and technically I'd have to cross someone
elses land to run a pipe from it (although they are entitled to use the
well water, and have the same covenants of maintaining the well too)
and I've no idea of it's going to be clean enough to drink, so might not
actually be worth it.

Gordon