Perhaps there's a 'grey' area - I always assumed that you owned everything upto the main unless your pipe goes off your property...if see what I mean. Theoretically, the main could curve around onto (under really) someones land and continue on - would this mean that that you'd be responsible for that part of the main? That stinks mate!! Pun intended!
It does though, doesn't it? Like everyone else is gonna come across the money to help a fix a common problem that is on someone elses land - bizarre. The ideal would of course be that the water co. split the bill and send it to each house thereby delegating sensibly who pays what.
I guess that makes sense tho'....