Every time I go to the supermarket (which is about every two weeks, because my wife is the main shopper) I pick up a gallon of water in the clear plastic (not the milk jug kind). They're the advertised brands like Poland Spring or Deer Park. They're about $1.50 - $2.00. At this point we probably have 50 of them. They are stored on shelves around the house. Cheap insurance and I don't have to carry in ten at a time when everybody else is trying to get them.