Treatments to Keep Water in Tanks

Water stored in tanks will serve as a home for algae and other organics if left untreated. This will be true for tap water as well as pond or well water since the residual disinfectants in tap water will dissipate over time. There are a number of chemical and other treatment options for keeping water in a tank and keeping it safe for drinking. The Federal Safe Drinking Water Act should serve as your guide on acceptable water.

Chemical Treatment

• The most common treatment method for stored water is to dose clean water with a chemical disinfectant. The most popular chemical for this is chlorine as it is cheap, readily available and effective. The dose rate for chlorine is 8 drops of pure chlorine bleach (no scents, colors or soaps added) per gallon of clean water. Stir thoroughly. You should still be able to smell chlorine 30 minutes after treating the water. If not, re-treat.

  If you do not have a proper bleach available, an 8 drop per gallon dose of iodine will also disinfect water for storage. The discoloration and unpleasant taste make iodine a less popular treatment than chlorine.

Ultra-Violet Water Treatment

• Ultra-Violet light kills organics in water. UV treatment works best when fully submerged into clear water as any solids blocking the light will defuse the effect.
  Use of UV for water storage is best done in a tank with some method of regularly stirring the water to ensure all of the water is exposed to the light. UV lamps require a power source.

Thermal or Solar Treatment

• Water does not have to be boiled in order for waterborne pathogens (disease-carrying organisms) to be eliminated. Pasteurization is achieved when water is heated to 65 degrees C (149 degrees F). Use of a black-painted metal tank or black plastic tank to absorb sunlight, and an external heat source or solar heating array to keep the water at pasteurization temperatures on a regular basis will keep stored water safe to drink.