How to Sanitize Water Holding Tanks

A clean water supply is necessary to prevent the spread of bacteria and illness and is therefore vital for maintaining the health of your family. If you notice that your water storage tank is emitting a stale odor, it may be an indication that the water has been left to sit unused in the system for too long. The best remedy is to sanitize or "shock" your entire water system, especially if you are using well water.

Things You'll Need

• Chlorine bleach
• Measuring cup
• Bucket
• Protective eye wear
• Protective gloves
• Long pants
• Long-sleeved shirt

Instructions

Sanitizing the water supply

1. Shock the entire water supply. One of the most commonly used water disinfectants is chlorine, which can be used to shock a water supply and deactivate most microorganisms living in the water. This method is commonly used by private well owners to sanitize the water supply to their homes. Shocking a water supply may not always provide enough chlorination in the water to disinfect the entire water supply. Depending on the size of your water storage tank, the water supply may need to be completely drained and refilled with treated water from a properly chlorinated well.

2. Determine the proper concentration of chlorine to use, the total volume of your water storage tank, and the time it will take for the chlorine to disinfect the stored water. For thorough sanitization of your water supply, the chlorine-to-water concentration must reach 200 mg/L. If you are using liquid laundry bleach, it is recommended that you use an unscented brand. Liquid laundry bleach contains 5.25% hypochlorite and requires 1.5 quarts per 100 gallons of water in the tank.

3. Measure the appropriate amount of chlorine product to be used into a bucket, then add it to the water supply tank. The chlorine will need to be left in the tank with the stored water for 12 to 24 hours without the water supply being used. After the waiting period, turn on the faucet nearest to the water storage tank and allow the water to run until you can smell chlorine. Once the chlorine smell can be detected, turn off the faucet and move to the next closest faucet, repeating until all of the faucets in your home have been opened up and the chlorine smell detected. The freshly chlorinated water will have moved through the entire water system now, but will require an additional 12 to 24 hours left unused in order to react properly.

4. Wait for the second 12-to-24-hour period to expire, then start with the faucet farthest from the water storage tank and repeat the previous process, moving to the faucet nearest the tank. This time you will want to allow water to run until chlorine can no longer be smelled. If the chlorine smell does not decrease, it is an indication that the chlorine has not properly dispersed through the system and will require more time to dissipate. In this situation you would need to acquire your drinking water from another source while the chlorine works through the water system. It would be safe, however to use water for purposes other than drinking.

5. Take a water sample from your storage tank to a professional to be tested. It may take more than one treatment to kill all of the bacteria in your stored water.

Tips & Warnings

• Always work in an area that is well-ventilated, wear eye protection, gloves, long pants and long-sleeved shirt when working with chlorine and chlorine products.

• Chlorine and chlorine products are volatile. Most harmful chlorine exposures are the result of inhalation. To limit health effects from exposure to chlorine, wash eyes and skin as quickly as possible with large amounts of water.

References

• Shock Chlorination of Stored Water Supplies
• RV Water Sanitizing Tip