How Much Chlorine Should Be Added to a Storage Tank to Kill Bacteria?
If you've been using well water for a long time or have been reading this blog frequently, you already know that chlorine is one of the most effective disinfectant methods.
It's low-cost, safe, and fairly easy to manage in water systems, making it the go-to for homeowners and municipal water districts alike. It's not just effective in water: chlorine can also be used to disinfect surfaces, pipes, and storage tanks in your home treatment system. But how much chlorine is enough? More importantly, how much is too much?
Today, we'll review the steps for sanitizing and disinfecting storage tanks and how to determine the amount of chlorine necessary for your application.
1. Clean the storage tank or reservoir. Remove debris and scrub the hose off any dirt or other deposits on interior surfaces. If possible, pump to remove any suspended solids or foreign matter in the water.
2. Scrub the interior surfaces of the storage tank/reservoir with a strong chlorine solution containing 1/2 gallon household bleach or 1/4 gallon pool chlorine for every 5 gallons of water.
3. Inspect the storage tank for cracks or leaks around the lid, vents, or manway. Properly screen any vents and tightly seal the lid to ensure no insects, rodents, or debris can enter the tank during normal operation.
4. Use the charts below to add the right amount of chlorine bleach to your tank and bring the chlorine residual to the desired level.
5. If you have time, bring the chlorine levels in your tank to 5 or 10 ppm and let sit for 12 hours or more. If a thorough disinfection is needed, but time is short, use a 50 or 100 ppm residual and let sit for 2 – 6 hours. Be sure to drain and flush your tank when using these higher chlorine levels, and avoid draining to septic tanks or into creeks, rivers, or lakes.
6. Be careful if you have a steel storage tank, as it can corrode over time and develop leaks after being sanitized with chlorine.
7. If your well is a low producer, consider having water trucked in. It's often cheaper and will prevent stress on your well by refilling the holding tank.
For the maintenance of your tank, consider cleaning and sanitizing at least once per year.
We hope this information helps you achieve clean, disinfected tanks and an efficient and sanitary whole-house water filtration system.
If you have any related questions or comments, e-mail us at support@cleanwaterstore.com, leave us a comment/message on Facebook, or use our online contact form. We're here to help!
Also, Read Our How-To Guide: How Much Chlorine To Add to Storage Tanks to Kill Bacteria
Frequently Asked Questions (FAQs)
1. How often should I sanitize my water storage tank?
We recommend cleaning and sanitizing your storage tank at least once a year. If you notice odor, sediment buildup, or bacteria in your water, it’s a good idea to sanitize more frequently.
2. What kind of chlorine should I use for disinfecting my storage tank?
Household bleach (5–6% sodium hypochlorite) works well for most home systems. Pool chlorine can also be used but should be diluted carefully. Always refer to the chart for correct dosage.
3. Can I use too much chlorine in my tank?
Yes—too much chlorine can corrode pipes, damage components, and leave an unpleasant taste or smell. Stick to the recommended parts per million (PPM) levels based on your disinfection goals.
4. Is chlorine safe to use in drinking water systems?
When used in the correct dosage and flushed properly after disinfection, chlorine is safe and approved for use in potable water systems by the EPA and CDC.
5. What if I don’t want to use chlorine?
There are alternative methods like hydrogen peroxide or ozone injection, but chlorine remains one of the most accessible and affordable options for well water treatment and storage tank disinfection.
