If your water supply is not known to be safe or has become polluted, it should be purified before use. Water purification is generally a two-step process.
Step 1: Clarify
Cloudy or dirty water must first be made clear. It should be passed through filter paper, fine cloth, or some other filter (like a coffee fileter). It should be allowed to settle, and then the clear water on top can be carefully drawn. Filtered or clear settled water should always be disinfected before use.
Step 2: Disinfect
Bringing water to a rolling boil for 3 to 5 minutes will kill most water-borne microorganisms. However, prolonged boiling of small quantities of water may concentrate toxic contaminants if present.
Adding 8 drops of fresh liquid household chlorine bleach (5 to 6% sodium hypochlorite) to every 4 liters (one gallon) of water will kill most microorganisms. Only household bleach without thickeners, scents, or additives should be used. The use of bleach does not address toxic contamination.
Commercial Water Filters
Commercial water filters can effectively filter and purify water contaminated with microorganisms, toxic chemicals, and heavy metals. Their effectiveness depends on design, condition, and proper use.
Use only food-grade containers. Smaller containers made of PETE plastic or heavier plastic buckets or drums work well.
Clean, sanitize, and thoroughly rinse all containers prior to use. A sanitizing solution can be prepared by adding 5 ml (1 teaspoon) of liquid household chlorine bleach (5 to 6% sodium hypochlorite) to 1 liter (one quart) of water. Only household bleach without thickeners, scents, or additives should be used.
Containers should be emptied and refilled regularly.
Store water only where potential leakage would not damage your home or apartment.
Protect stored water from light and heat. Some containers may also require protection from freezing.
The taste of stored water can be improved by pouring it back and forth between two containers before use.