Getting a house connected to the mains (water)

[supergrains]

Inherited a house in the country which get its water from a well, and the waste goes into a septic tank.
The amount of water we can extract from the well day-to-day isn't enough for modern usage, and we want to rent the house out, so we can't ask tenants to restrict their water usage.

There is an outside water mains tap, near the house, which isn't used very often, but works and has good pressure. The tap is there because a long-deceased relative made a deal with a water company (no idea who, and I know they haven't billed for possibly the whole time its been there) to either swap or use a part of his land for this connection to the mains....no idea when this was done, but maybe 50-30 years ago?

We would like to start investigating how to get the house connected to the mains, but haven't the foggiest idea, and from my own dealings with water companies (admittedly a completely different area of the country) they are a TIA to deal with so I haven't been keen to start ringing round.

Any ideas where I can start? Are they going to come after me for 50-30 years of bills?

I’ve heard about similar arrangements for friends. One- a village was put onto mains gas and it had to go under a farmer friends field. His house was connected for free and he doesn’t pay for gas. It does mean his field is dug up for maintenance etc though.
There is a limit on what they could bill you anyway and there is unlikely to be a meter.
I would suggest contacting the local water board. Or company. Is the water board a thing?! And asking about the arrangement and explain you want to get a house connected, what has to happen and maybe renegotiate the deal?