Ron ap Rhys - Remember, you will need to filter more than just drinking water. Water to add to dehydrated food, water to clean with, and so on. I used to live in 110 year old miners cabin, we lost water for about 2 months over a brutal winter (it would freeze, warm up and thaw, freeze again...), we used about 1.5 gallons per day of filtered snow melt for drinking/cooking and another 1.5 gallons of unfiltered water for bathing, toilet...etc. It sucked, but we got thru it.

A "normal" emergency you would be fine. I have an elderly neighbor or two that I always anticipate helping out.