I almost to the point....

[henry quirk]

As I (unavoidably) share the water main with the others, for that one time repair, yeah, I'd pay my share of that half-price service.

The problem you present, of course, illustrates directly (and only) the flawed nature of living in such close confines with others (so close that shared water sources are unavoidable). Your problem doesn't, I think, negate my essential argument of paying for what one gets (and not paying for what one has no need or use for).

In fact: your problem, seen in a certain light, supports my position because, in your scenario, I pay for what I need (the water main) and don't pay for what I don't need (the general plumbing).