In a lot of cases when city water came through years ago people were opposed as well water was "free" and they had to pay for city water. Most municipalities forced the homeowners to hook up to city water when it was plumbed in. Most folks used their well for chores until something went out on it. The previously mentioned test is a good idea. Most wells were just shut down because the owner got tired of maintaining it. Or got tired of lugging all the extra hoses around to use it. Back then most of them had steel tanks as well and if it weren't cycled through as a normal household would use it, often the pipes would clog with rust and or the tank would rust out and spring a leak. Or the points would go out. So on and so forth. So I in general I guess you could say that city water shut down most wells as it was no longer economically feasible to buy parts for it just to wash the car and so on.
Good luck to you.