Kentucky Cisterns: Sizing, Siting and Disinfection per UK Extension

University of Kentucky Extension publication IP-4, "Cisterns for Kentucky" (issued 9-90; the number "IP-4" is taken from the URL path and does not appear in the text, so dated; check for a newer edition). Only stated points are included.

Cisterns are described as a practical household source where well or spring water is scarce or too impure to treat. Properly designed and maintained, they can be reliable.
Sizing depends on rainfall, roof area, materials and daily use. Kentucky averages about 40 inches of rain in the north and 50 in the south. Example given: a 12 x 12 x 9 ft cistern holds a 48-day supply for four people at 50 gallons per person per day.
Gutters must match roof size; a roof washer diverts the first flush; overhanging trees add organic material.
Siting: firm soil, floor sloped toward a sump under the manhole, overflow screened with 1/4-inch hardware cloth, inlet sealed against surface water, raised curb on the 24-inch manhole, whose cover must be heavy or have a lockable cap.
Materials: poured reinforced concrete "makes the best cistern" when properly built; block cisterns crack more and leak at joints.
Disinfection: chlorine pump at 2 mg/liter free chlorine with 2 to 5 minutes contact (5 recommended), or batch treatment of 1 ounce of 5% bleach per 200 gallons, weekly if no new water is added. Contact time also depends on pH, temperature and bacteria. Activated carbon is not recommended for water entering a cistern (it may follow decontamination, for taste and odor).
Test periodically for coliform; clean and disinfect every five years or more often (for example with leaves, blowing dust or wood or coal stoves nearby).

Not verified: current Kentucky rules or health department guidance on cisterns, and pump selection for pressurizing; the publication does not cover pumps.

General information only. Not health, plumbing, legal or code advice. Confirm with your county health department.