How to Chlorinate a Water Heater and Remove Bad Odor

Maintaining a clean and odor-free water supply in your home is essential for both health and comfort.

One common issue that many homeowners face is the presence of unpleasant odors or the occurrence of black water emanating from their water heaters.

Fortunately, there's a straightforward solution to these problems: chlorination. Learning how to correctly chlorinate your water heater can effectively eliminate these nuisances, ensuring your water is clean and safe for use.

While chlorination might seem simple at first glance, it requires careful attention to detail to ensure it's done properly.

Importance of chlorinating water heaters

Chlorinating water heaters is a crucial maintenance practice that serves multiple purposes in preserving the quality and safety of household water supply.

Regular chlorination can significantly prevent unpleasant odors that often emanate from water heaters due to bacterial growth and the decomposition of natural materials like sediment, minerals, and rust, which accumulate over time.

These odors are not just nuisances but indicators of potential water quality issues that could affect the health of household members.

Bacteria, particularly Legionella pneumophila, which is responsible for Legionnaires' disease, thrive in warm, stagnant water conditions typical of water heaters.

Regular chlorination disrupts the growth of these microorganisms, ensuring the water remains safe for use. Besides health concerns, sediment buildup can also affect the efficiency and longevity of the water heater.

Chlorine, being a potent oxidizer, breaks down and helps in the removal of these sediments, maintaining the heater's efficiency and prolonging its lifespan.

Overview of chlorination methods

When it comes to chlorinating water heaters, there are primarily two methods: the use of a continuous chlorine feeder and periodic flushing with common household bleach.

In this discussion, we will focus on periodic flushing with household bleach. This traditional method involves manually adding a specified amount of bleach to the water heater tank and then flushing the system to distribute the chlorine effectively.

The primary advantage of this method is its simplicity and cost-effectiveness, as it can be done with regular household bleach and does not require any special equipment beyond basic tools for draining and refilling the tank.

This approach is ideal for periodic maintenance and can be very effective at removing odors and disinfecting the water system.

However, it requires more effort from the homeowner and needs to be done regularly to maintain water quality, typically every few months depending on water usage and quality.

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How to chlorinate a water heater properly: Step-by-step guide

Gas water heater
  • Ensure safety first: Before starting, turn off the power supply to your water heater. If it's gas-powered, shut off the gas valve. Also, close the main water supply valve to stop water from entering the heater during the process.
  • Release pressure: Open the nearest hot water tap to your water heater and the temperature and pressure relief valve (usually located on the top of the unit) to relieve any built-up pressure inside the tank.
  • Prepare for draining: Attach a garden hose to the drain valve found at the bottom of the water heater. Make sure the other end of the hose is positioned in an area where it can safely drain, such as a floor drain or an outdoor area.
  • Drain the tank: Open the drain valve to let out a few gallons of water-enough to make room for the amount of chlorine you'll be adding. This helps to ensure the bleach doesn't overly dilute upon entering the tank.
  • Add chlorine: Choose an access point for adding the chlorine-either the opening left by removing the temperature and pressure relief valve, the anode rod, or the hot water outlet pipe. Calculate the amount of chlorine needed (typically, 1 gallon of household bleach for every 30 gallons of tank capacity). Pour the correctly measured bleach into the water heater tank through the chosen opening.
  • Refill the tank: Close the opening used to add chlorine and open the main water supply valve to fill the tank. Ensure the tank is completely full before proceeding to the next step.
  • Let it sit: Allow the bleach solution to sit in the tank for at least one hour, though two hours is often recommended for thorough disinfection.
  • Flush the system: After the bleach has had time to work, open all hot water faucets in your home to flush the chlorinated water through the pipes. Continue flushing until you no longer smell bleach.
  • Final rinse: Reconnect the garden hose to the drain valve and open it, along with the water supply valve, to flush the tank with fresh water. Let the water run through the tank and out the drain valve until it runs clear and is free of any bleach smell.
  • Close and refill: Shut the drain valve and remove the garden hose. Allow the tank to refill completely by ensuring the water supply valve is open. Open a hot water faucet to release any trapped air in the system until water flows steadily.
  • Check the anode rod: Before turning the power back on, inspect the anode rod for any signs of wear or corrosion. If necessary, replace the rod to extend the life of your water heater.
  • Power on: Once the tank is refilled, and you've ensured there are no leaks, turn the power supply back on. For gas water heaters, relight the pilot light according to the manufacturer's instructions.
  • Test for odor elimination: After the water heater is back in operation, check the hot water from a tap for any remaining odors. The bad smell should be eliminated, and your water quality significantly improved.
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Can chlorine damage water heater?

Using chlorine in the recommended concentrations for water heater disinfection generally does not harm the appliance. However, excessive chlorine can corrode metal parts, so it's important to follow dilution guidelines closely and flush the system thoroughly after chlorination. Consult the manufacturer's guidelines or a professional plumber if you have concerns about chlorine use.

Will chlorination affect the taste or smell of my water?

Properly done, chlorination should not leave a lasting taste or smell. After thoroughly flushing the system post-chlorination, any residual chlorine taste or smell should be eliminated. If you notice a persistent chlorine odor or taste, additional flushing might be necessary.

Can I chlorinate my water heater myself, or should I hire a professional?

While many homeowners feel comfortable performing the chlorination process themselves, especially with periodic flushing using household bleach, it's important to follow safety guidelines carefully. If you're not confident in doing it yourself or if your water heater requires a more complex maintenance routine, hiring a professional is advisable.