We're fortunate to be on a township water system, gravity fed; it has its faults (the system has been cobbled together over quite a few years and has about 200 customers on it) but the water is excellent and, although we live very close to Lake Michigan, the water comes from Lake Superior - or so I've been told by people who understand geology a lot better than I do!
It IS kind of scary to have an extended outage like that; makes us realize just how much we depend on all the "modern comforts." And then there's my husband's (older) sister and her husband, both in their mid 80s; about a year ago they installed a big, expensive, whole-house Generac generator for just this sort of thing; it ran for 2 days and then "blew a gasket" (or something)... but fortunately their power came back just a day later.