I have several ways around here to filter & purify water , some are store buys and others are more off the wall . What most people don't realize is that for short term water needs even without a powder supply or well pump , their Hot Water Heater holds about 60 gal of pottable water - ready to use .
Also the toilet tank holds another gal or so , along with maybe 3 gal just in the piping of their home , all very drinkable water .
stimpy