How to Treat Cistern Drinking Water With Chlorine Tablets

Treating cistern drinking water with chlorine tablets may have to be a regularly scheduled maintenance or a one-time shock treatment. Contamination can come from many sources, and if the cistern is compromised, it can be shock treated with chlorine tablets. Regular maintenance with chlorine tablets will depend on water usage. By following a basic procedure, you can treat cistern drinking water with chlorine tablets in a short period of time and have safe, clean water for your family.

Things You'll Need

• Chlorine laundry bleach (1 gallon) 5-gallon plastic bucket Scrub brush Cloth bag High-test calcium hypochlorite (HTH) tablets Polyethylene rope

Instructions

Clean the Cistern

1. Remove the cover to the cistern and inspect the water. If the water has debris in it or on the surface, drain the cistern and clean the inside surface with a bleach solution and scrub brush.

2. Make a solution of ½ gallon laundry bleach to 5 gallons of water for cleaning the inside of the cistern tank.

3. Scrub all of the inside surfaces with the brush and chlorine bleach solution thoroughly, then rinse with clean water.

4. Refill the cistern, paying particular attention that all of the integrity seals are in good shape. You may have to repair any cracks or seals that keep debris from falling into the cistern.

Shock Treatment

1. Calculate the volume of the cistern (see Resources below). The volume of the cistern, capacity in gallons, is important so you can add the correct amount of HTH tablets to the water.

2. Add one 4-oz. tablet of 65 to 75 percent HTH for every 100 gallons of cistern water into a cloth bag.

3. Tie the bag closed with the polyethylene rope and lower the bag and tablets into the cistern water.

4. Move the bag in an up and down motion until the tablets have fully dissolved in the water.

5. Run the water throughout the home's water piping system until a strong chlorine smell is noticed. Allow the water to sit in the pipes for a full 24 hours.

6. Flush the entire water system--cistern to water pipes--of the chlorinated water.

7. Refill the cistern with fresh water and treat the water with one 4-oz. tablet of HTH 65 to 75 percent chlorine as in Step 3. You can leave the bag hanging in the cistern if you can close the top to seal the cistern tank. If you cannot seal the cistern, dissolve the tablet as in Step 4.

8. Maintain the chlorine tablet treatment for every 10,000 gallons of water usage or as often as needed.

Tips & Warnings

• A carbon in-line filter system will help to eliminate the chlorine bleach smell from the drinking water. It should be removed whenever you need to shock treat a cistern water supply.

• Test the drinking water through a reputable agency after any modifications to your water supply or contamination.

Resources

• Water Quality and Chlorine
• Shock Treatment With Chlorine