Richard Arconti 
If you get your water from a well, you need to periodically disinfect your water supply. In fact, it is generally recommended that you shock-chlorinate your well once per year. Although, if you suspect that your well has become contaminated from an outside source, you will want to chlorinate it immediately. But how long does it take to get chlorine out of well water?
After shock chlorinating your well, it generally takes 24 hours to reach a safe concentration level, depending on the size and type of your well.
By disinfecting a private well, you can reduce and sometimes even eliminate harmful bacteria. Chlorinating your private well can be a simple DIY process. If you do choose to shock-chlorinate your well yourself, be sure to obtain detailed instructions and follow them carefully.
How Long Does It Take For Chlorine To Leave Plumbing After Shock Chlorination?
Once chlorine is introduced to your well, it will take approximately 30 minutes to 24 hours for the chlorine to fully circulate and exit your home’s plumbing. The time it takes for chlorine to be removed from a private well depends on the type and depth of the well.
- Dug Wells (Bored Wells): 10 – 30 feet deep
- Driven Wells: 30 – 50 feet deep
- Drilled Wells: Can be hundreds of feet deep
If you have a shallow well that is relatively small, it may take under one hour to completely flush the system, while a deep drilled well may take 24 hours.
It is best practice to turn on all of your fixtures and faucets to allow the chlorinated water to spread throughout your home’s plumbing system – then turn off the faucets and allow the chlorine water to sit. As the chlorine circulates, it will disinfect the plumbing, fixtures, and appliances.
If you decide to disinfect your well, it is essential to make sure you give the process time to complete before you start removing the chlorine from the water. Chlorine needs a minimum of 30 minutes contact time with water to properly disinfect it. This will give the bleach time to destroy the bacteria, and then you can begin the flushing process.
After the proper amount of contact time and as the strong chlorine odor from the well goes away, you can turn back on all your faucets until the chlorine water runs out. You also need to ensure your water heater is thoroughly flushed, therefore you will need to run your hot water longer.
How Long Should You Wait To Use Water After Chlorinating A Well?
You should not use the water after chlorine is introduced for 12 to 24 hours so you can flush all of the chlorine from your home’s plumbing system. After 24 hours, the water will likely be safe to shower in, but you may want to wait 48 hours before drinking the water.
After you complete the chlorination process, run your water until each faucet is no longer producing a chemical scent. A safe concentration of chlorine in water does not have any odor, so if you can detect a smell, it is not suitable to consume. Don’t forget to do this with outdoor spigots, showers, and both hot and cold faucets.
Symptoms of elevated levels of chlorine exposure include:
- Stomach discomfort
- Burning sensation in throat and lungs
- Chest tightness
- Coughing
If you are especially sensitive to chlorine exposure, you should consider adding additional time for the chlorine levels to reduce. You can reduce exposure by taking shorter showers, using rubber gloves to wash dishes, and using bottled water.
How To Know If Shock Chlorinated Well Water Is Safe To Drink?
The most accurate way to know if chlorine levels in water are safe to drink is to test the water. Once you have begun flushing your water system, you should run the water until a chlorine paper test strip indicates a safe level of chlorine.
The Environmental Protection Agency (EPA) has set the maximum acceptable amount of chlorine in drinking water at 4 PPM. The optimal range is between 0.2 PPM – 0.5 PPM so water will remain bacteria free while not having unpleasant taste or odors. You may need to take several tests from different taps in your home to ensure the free chlorine levels are acceptable.
Once you confirm the chlorine concentration is safely below the EPA acceptable level, you can resume using your tap water for drinking.
How To Know If Shock Chlorination Worked
It is important to test your well water 2 weeks after the initial chlorination process to ensure the treatment worked. Once you confirm the coliform bacteria is eliminated from the water supply, you can begin using it for drinking and cooking.
Some chlorination kits will come with a bacteria test kit to use as a follow-up. If not, a coliform bacteria test kit typically cost $40 – $60.
Until you find out that the water is safe to use, it is important to boil the water or use bottled water. Even if you test the water right away and it is safe, it is best to retest the water in a week or two to make sure it is still safe.
Then if you have had your water tested twice by an accredited laboratory and they find it is safe to use, you will know that the shock chlorination worked.
Common Well Water Chlorination Mistakes
There are a few common mistakes well owners make when they perform the chlorination procedure. Keep these in mind while performing the shock chlorination process.
- It is not advisable to sanitize a well system with swimming pool chlorine or household bleach. Neither of these was designed for this use. Pool chlorine and bleach do not treat the contaminated areas and can leave behind odors as well as some trace elements like heavy metals.
- Chlorine is a powerful base chemical that can cause severe burning to the skin and eyes. This means you need to be cautious whenever you are handling chlorinated water or near the chlorinated well.
- Shock-chlorinated water can be highly toxic until the system has had enough time to circulate and flush. Make sure everyone within the household is made aware of the shock-chlorination procedure and not to drink or use the water until enough time has passed.
- Plants, animals, and septic tanks can all be negatively affected by high chlorine levels. This means you should never flush your chlorinated system onto lawns, near septic tanks, or into aquatic ecosystems.
- Shock chlorination is effective, but once the chlorine levels decrease, bacteria can return. Make sure to test your well water after the process is complete to ensure it is effective.
Shock Chlorination Alternatives
Shock chlorination is an effective technique for eliminating microorganisms from well-water systems. However, it is not the only way. Here are two alternatives that can be just as effective at protecting the safety of your water supply while eliminating the dangers of high concentrations of bleach.
UV Light Disinfection
Ultraviolet technology is one of the newest methods of protecting private well water sources from harmful microorganisms. Instead of using chemicals to eliminate microorganisms such as coliform bacteria, it uses ultraviolet light to disinfect and kill viruses and bacteria. This can be extremely effective in killing up to 99.99% of bacteria and viruses and is often combined with a pre-filter to remove larger contaminants that could absorb or reflect the light.
Chemical Injection Systems (Chlorine and Hydrogen Peroxide)
Shock Chlorination can eliminate harmful bacteria and other microorganisms from your system in a short period of time. However, once the chlorine levels in your water decrease, these organisms may return.
A chemical injection system can eliminate this threat, however, by continuously introducing small amounts of chlorine or hydrogen peroxide into your water supply. Often these systems are combined with a filtration element that removes particles and unpleasant flavors. This can eliminate bacteria and other contaminants from your system, ensuring that your water is always safe and pleasant to drink.
Regular Well Maintenance
The most important way to protect your water from potential contamination is to perform regular maintenance. Professional service performed at least annually can ensure the well and system are clean and free of mechanical or structural issues.
This should include a check of the pressure tank, well casing, and water system. So long as these systems are in good working condition, the chances of contamination are much lower.
