I don't know about "risk you take", but how about "risk you have to manage yourself".
The problem is, even when you do plan for the unexpected, something even more unexpected has a habit of happening!
Personally, I'd ask them now about whether they can sell you water via a bowser if your supply does completely dry up. If they say yes, then you know you have a contingency plan. If they say no, then you know you need to get some IBCs in, and an arrangement with a friend on mains water.