How to Clean Out a Very Old Cistern That Holds Drinking Rainwater

Cisterns -- large tanks used to store water -- have the unfortunate tendency to attract uncleanness, such as bacteria and dirt. This quickly complicates the fact that cisterns are often used to store water, especially in rural areas where people may not have ready access to public water, or for the ecologically conscious who prefer using conserved rainwater for a variety of uses. Very old cisterns, in particular, often become a dirty home for unpleasant growths like bacteria. Fortunately, cleaning old cisterns is not a conceptually difficult task, although it can be a dirty, time-consuming and tiring one.

Pipe or bucket
Power washing tools or a strong hose
Scrub brushes
Bleach (optional)
Cover (optional)

Instructions

- 1
  Empty the cistern of water. This can be the most challenging part of the job if you don't have access to a water vacuum, or if the capacity of the tank is particularly large. Use a bucket to scoop water out of a smaller cistern.
- 2
  Remove any residue left in the cistern. If it was dry to begin with, this may include sweeping up large chunks of dirt, leaves or even small animals that may have become trapped.
- 3
  Spray the cistern down with the power washing equipment or powerful hose. Use the force of the water to clean dirt out of the crevices. Plan carefully to avoid quickly filling the cistern with dirty water again.
- 4
  Drain the cistern again.
- 5
  Spray the cistern with a bleach and water solution, if desired. This step is necessary to kill bacteria that may be growing. The Centers for Disease Control and Prevention recommends a ratio of 1 cup of bleach to 10 gallons of water for scrubbing purposes.
- 6
  Scrub any remaining dirt from the cistern. Rinse well and drain.

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