I have some 5 gal pails that are square and have a 2 1/2" filler hole in the top and a small capped vent. I've used these for water on small camping trips and they seem to work great. My question is, how do you store water and keep it from getting stagnant for long periods of time? I want to get somewhere around 50 of these full and stocked up......any ideas on how to store H2O for long periods?