Here is some useful information on purifying water for use, whether it is stored in barrels at home, or collected elsewhere:
1. If water is cloudy, smelly or therwise polluted, strain it through a paper towel or several layers of clean cloth into a container in order to remove any sediment or floating matter.
2. Water that is boiled vigorously for one full minute will usually be safe from harmful bacterial contamination. Boiling for 3-5 minutes is safer, if you have heat to spare.
3. If boiling is not possible, strain the water as above and treat by adding ordinary liquid chlorine household bleach (4-6% chlorine) or tincture of iodine (from your medicine chest–2%chlorine) in the following amounts.
a. CHLORINE: Add 2 drops (with eye dropper) per quart of clean water, 4 drops per quart of cloudy water. (This equates to 1/2 tsp. per 5 gallons of clean water, or 1 tsp. per 5 gallons of cloudy water.
FOR A 55 GAL. DRUM, USE 2 TBSP / 4 TBSP. of bleach).
b. IODINE: Add 5 drops per quart of clean water, 10 drops per quart of cloudy water.
Mix thorougly in container. Let it stand for 30 minutes. A slight chlorine odor should be detectable in the water; if not, repeat the dosage and let the water stand for an additional 15 minutes before using.
It is a great idea to store powdered drink mix to improve the taste of stored water. Drink mix and disposable drinking cups should be part of your emergency supply.