Private Wells and Private Sewers

[Elenfair]

We're currently househunting. We came across a listing where the water and the sewer were "private".

I think I understand the basics - it's private, not public, duh, and therefore the responsibility of the owner if something goes awry.

What I want to know is: what does ownership of a well/sewer system entail, for maintenance and such? Help? Anyone? Bueller?