A Step-By-Step Guide on How to Shock A Well the Right Way

Almost all households with substantial water reservoirs, wells, and swimming pools, are familiar with shock chlorination.

Often, they observe this practice to remove bacteria and get rid of contaminants from the cold water part of the water supply system.

However, this should be taken seriously if you plan to do this process. To eliminate pathogens in the water, you should prioritize your safety.

Knowledge is vital to ensure you are doing the right thing. If you are new to shock chlorination, worry not! 

This step-by-step guide will help you know what shock chlorination is, when you should apply it, its effectiveness, safety precautions, and the whole process from start to finish.

What is Shock Chlorination?

Shock Chlorination

Shock chlorination is a process that involves using sodium hypochlorite. It is a chemical that can be in a powder or liquid form. The granular or powdered form has high chlorine content and is water-soluble.

On the other hand, liquid sodium hypochlorite is usually available in laundry bleach or chlorine products.

The term “shock” refers to a quick procedure. Another term for shock chlorination is rapid chlorination. People usually observe and practice this process to improve the quality of water.

It is applied to water systems, water wells, and swimming pools. It restores appropriate disinfection of your water reservoir in a short period. It will also be helpful when the pool or well turns green at the beginning of the season.

There are two types of shock chlorine: stabilized and unstabilized. The stabilized (dichloroisocyanurate) chlorine contains an isocyanuric acid stabilizer that prevents chlorine from degrading when exposed to UV light.

It lacks a stabilizer, and it is more susceptible to light effects. Calcium hypochlorite (calcium hypochlorite) is much more unstable and should be handled cautiously.

When Should Shock Chlorination Be Used?

Of course, we know that water is one of the necessary variables for us to survive and live. And, for us to maximize its benefits, we need to make sure it is free from contaminants that might be detrimental to our health.

There are several important reasons to disinfect your water well and home water supply. Yet, the main thing that will tell you when to disinfect your well at home: your water did not pass the fecal coliform test. 


Fecal coliform may degrade the quality of the water. This type of bacteria may occur in contaminated water due to an overflow in sewages. Nonpoint pollution from animal and human waste can also cause the fecal bacteria to grow in water reservoirs. 

Plumbing repairs can also induce fecal bacteria when you do repairs and maintenance activities on a well. Thus, when you open a well for repair, the health code requires disinfecting it before reusing it.

There are three instances when households conduct the said test:

  • whenever property ownership changes
  • when required by mortgage lenders and real estate firms.
  • If family members regularly suffer from nausea, diarrhea, or other gastrointestinal issues

A fecal coliform test usually costs less than $30, and results are generally available within a week or two of the sample.

Other reasons to apply shock chlorination include:

  • when a there is new well or an underused well is put back into service
  • if the results of yearly water tests reveal the presence of bacteria
  • if a well is opened for any installation, repair, or maintenance
  • when the well is engulfed in floodwaters (standing water around or covering the good casing)
  • if the water in your well appears murky or foggy after it has rained
  • if there are signs of iron bacteria or sulfur-reducing bacteria in the well, such as slime (biofilm) or odor,

Is Shock Chlorination Effective?

Chlorine has the power to fight and inactive almost all pathogens thriving in water. Here is the list of pathogens it can eliminate:


  • Burkholderia pseudomallei 
  • Campylobacter jejuni
  • Escherichia coli 
  • E. coli (entero-hemorrhagic)
  • Salmonella typhi
  • Shigella dysenteriae
  • Shigella sonnei
  • Vibrio cholerae (smooth strain) 
  • Vibrio cholerae (rugose strain)
  • Yersinia enterocolitica 


  • Coxsackie A 
  • Coxsackie B
  • Echovirus
  • Hepatitis A 
  • Poliovirus
  • Adenoviruses
  • Noroviruses
  • Rotavirus


  • Entamoeba histolytica
  • Cryptosporidium parvum
  • Toxoplasma gondii 
  • Giardia intestinalis

In trying to battle against these pathogens, note that they have different tolerance to chlorine. As a result, they too require different chlorine concentrations and time exposures.

For instance, salmonella needs 20 minutes of exposure, while Hepatitis A needs less than 1 minute. 

It is essential to know what specific contaminants are present in your water first to know the proper treatment. However, in urgent instances where you are unsure of the inactivation time, remember that the longer, the more effective it gets. 

two kinds of water

Chlorination is a powerful antibacterial and antiviral agent. It cannot, however, disinfect all waterborne diseases. Some diseases, such as protozoan cysts, resist chlorine’s effects. 

Does Bacterial Contamination Reoccur?

Being complacent after shock chlorination can be pretty dangerous since there is a chance that water contamination might reoccur. It can happen because of the following reasons:

  • a nearby septic system that isn’t working
  • a means of bringing surface water into a well, such as:
  • a wrong well location
    • lack of a well cap or a well cap that is incorrectly installed or loose
    • faulty grouting or other flaws in the well construction
    • a shattered well casing

How Often Should You Show Your Well?

Homeowners with private wells should get their water tested for pollutants like bacteria every 3 to 5 years. If these tests reveal the presence of contaminants, chlorinating the well may be an option for resolving the issue.

Precautions Should Be Taken Before Shock Chlorination

Usually, licensed well drillers are knowledgeable in doing shock chlorination. As we discussed earlier, this process removes pathogens from holding tanks, well water, water supply systems, and well casings. 

Shock chlorinating your well all by yourself is pretty challenging. However, it is not impossible. You just need to observe specific precautionary measures to guarantee your safety during the process.

Here are the safety practices you should remember:

Too much chlorine solution concentration is not safe

The primary step is to make sure you are wearing proper gear. That includes appropriate clothing. You should also protect your eyes from sudden splashes by wearing goggles.

A protective apron will save your dress from discoloration and your skin from getting contact with the chlorine. In handling the chemical, boots, and gloves are also important. Remember, chlorine is a corrosive chemical, which means it can cause damage to your skin.

safety equipments

Find a well-ventilated area

Never mix in a constricted and closed space when mixing the chlorine solution. Find a well-ventilated area in doing this step.

Exposure to a high dosage of chlorine can lead to lung injury and respiratory failure. When it enters your ears and nose, it may cause a sinus infection, making you suffer from irritation and swelling.

Beware of high chlorine levels in water after shock chlorination

Do not immediately use and consume newly shocking water. Instead, prepare an alternative source of drinking water for the meantime.

Everyone inside the house should know, especially children, to avoid ingesting the water. Accidental ingestion of this chemical in high concentrations can lead to convulsions or vomiting. If one of the household members had, let them drink milk or water instantly.

Observe the 12-hour or 24-hour rule

Remember our discussion earlier? Chlorine should have its exposure time for it to become effective.

Similar to the previous step, let everyone know inside your home that they should not touch the treated water for twelve to twenty-four hours. By doing this, you are making sure that contaminants are truly gone.

Store water beforehand

Store enough water to last a family of four for 24 hours, including water for animals. Consult an Environmental Health Officer or a Public Health Inspector for advice on disinfecting your water supply properly.

It should be noted. Know that the water is dangerous to drink and must be boiled for one minute or treated before use. 

You should keep the water pump from causing an electric shock

Turn off the pump circuit breaker before removing the well lid or cover. Turn the electricity back on during the shock chlorination process, but make sure to turn off the pump circuit breaker before reinstalling the well cap or cover. Wear waterproof rubber boots.

Components of the water supply and treatment devices should be safeguarded

Shock chlorinating a water supply system has the potential to harm pressure tanks, specific filters, and filter media, as well as other treatment equipment.

Shock chlorinating a water supply system

Disconnect all carbon filters and reverse osmosis equipment connected to your home’s water pipes before you begin. The robust chlorine solution may harm these filters. 

Some iron filters, water softeners, and sand filters, on the other hand, may not be damaged. Before shock chlorinating your water supply system, check with component makers to see how you can bypass or safeguard this equipment if required.

Wait for one to two weeks

Before finally drinking your water, wait for at least one to two weeks after the shock chlorination. By then, test the water for coliform and E.coli presence. If the results are precise, the water is already safe to drink. 

However, if the results go otherwise, another round of shock chlorination is not preferable. At this point, there is for sure a source of contamination.

Thus, you need to find it. You can ask for assistance from a professional licensed driller or contractor. You should also take into consideration installing a continuous disinfection treatment system.

  • Before attempting to chlorinate the well, it is critical to examine the following before starting the chlorination procedure, ensure the well is in good working order.
  • Examine the well’s condition, including its location, well casing, and sanitary seal 
  • Examine the plumbing system for leaking pipes, a pressure tank, and a cross-connection.

Beware of the chemicals you are mixing

To be safe, do not mix any chemical or compound with chlorine. Ammonia, when mixed with chlorine, can form a toxic gas.

There are times when it produces an explosion. Exposure to chloramine gases may lead to nausea, chest pain, watery eyes, wheezing, irritation of the eyes, mouth, and throat, and coughing.

Prepare clean water on your side

Accidents are part of any activity. They are indeed undesirable; hence we should take precautionary measures to lessen their damage. Before you start shocking the well, get a huge gallon or container. Fill it with fresh water and keep it close to you. 

Use this water if there is chlorine in contact with your skin and eyes. Flush the water in the area for ten to fifteen minutes. However, if the solution gets inside your eyes, immediately go to the doctor after thorough rinsing.

10 Steps on How to Shock a Well


We mentioned earlier that the first step to shocking your well is to have a water test. When your water is tested unacceptable, it is time to do the shocking. Here are the steps in doing the process by yourself.

1. Clean and open the Well

Turn off the electricity that flows through the pump. Clean the surroundings of the house or wellhead. You should make sure that all foreign and loose debris is not present. After which, start removing the sanitary cover or healthy cap.

If you think that the cap already needs repair or if it is not a sanitary cap, have it replaced already. 

Place a chlorine solution to clean up your wellhead, cap, and bucket. We recommend a ratio of one cup of bleach and a half-gallon of water.

Pour the chlorine solution into an aperture at the top of the well because well caps differ. Hence, the difficulty of this phase depends on the type of well you have.

2. Inspect Wiring

Before pouring the bleach into the water, inspect the wiring to see any cracks. Also, know if there are splices on the wire nuts, especially if they are not waterproof.

If you have any concerns about whether you can safely wet wire with a hose or bleach, stop immediately and get advice from a qualified electrician.

3. Determine the amount of bleach

Know the diameter of the well first. Then, measure the depth of the water inside the well. The amount of chlorine in the mixture should depend on the volume of the water that needs treatment. It is essential to know this information before proceeding with the procedure.

You can go to your local Department of Health office to know if any data on file indicates a Uniform Water Well Completion Report. The report will tell you the depth of the well and the static water level.

To quickly know the amount of water inside your well, subtract the top of the well down to the water’s surface to the total depth of the well.

The most straightforward technique to introduce chlorine into the well is to use a clean 5-gallon plastic bucket to mix the appropriate amount of bleach or dissolve the calcium hypochlorite pellets or powder with fresh water. 

Fill the bucket with chlorine solution and pour it into the well. Note that the volume of liquid bleach required to disinfect certain deep or big diameter wells will be higher than 5 gallons. Pour the bleach directly into the well in these circumstances.

Please refer to the table below to know the amount of bleach for your well.

Amount of water in well (ft)Well Casing in Diameter (in)
102 cups2 cups2 cups
502 cups2 cups3cups
1002 cups3 cups4 cups
3003 cups4 cups10 cups

Reduce the quantity of bleach you use by half.

If just the well has to be disinfected, use 1 cup. If the following applies, you may need to increase the amount of bleach solution:

  • There are additional buildings in the water system.
  • Has a lot of pipes or storage space, or
  • If your well has been flooded, contains nuisance bacteria, or is a dug well, disinfect it.

4. The right type of chlorine bleach


You should not just mix any bleach to shock your well. It should be plain laundry bleach such as Purex, Chlorox, or any generic brand. Avoid using bleach with special scents or with soap detergents. Note that it should contain five (5) to six (6) percent of sodium hypochlorite. 

5. Pour the bleach

Use a funnel when pouring the bleach into the well. This is to avoid sudden spills. Gently pour the mixture and beware of the other components of well caps, such as wires, since they can cause corrosion.

6. Mix the Chlorinated Water

Now, turn on your circuit breaking to the pump. Connect a water hose to the nearest hose connection. Maintain the funnel attached to the mouth of the well.

Let the water flow out from the hose for about 10 minutes away from the well. When the water coming out turns clear, turn off the water.

In a repetitive circular motion, fill the well with water. Then, put the hose inside the well, and turn on the water again. Do this for 30 minutes right after the bleach smells from the garden house. 

Turn the pump’s circuit breaker off. Using commercially purchased water, rinse the well components. The bleach solution is washed away during the rinsing process, which helps to prevent rusting. Replace the well lid and wires. Turn the pump’s circuit breaker on.

7. Check if chlorinated

Next step is to bring the bleach solution into your water system. To test if there is a presence of chlorine in your water:

  1. Use chlorine test papers.
  2. Run the water until the paper indicates a minimum of 50 ppm.
  3. If the concentration is less than 50 ppm, proceed to STEP 5 and add more bleach solution, then repeat STEPS 3 and 5.

8. Hold chlorine in pipes

Turn the pump’s circuit breaker off. To prevent anybody from using the water, post notices or turn off taps and fixtures. Allow at least two hours, ideally twelve hours, or overnight for the bleach solution to settle in the water system.

9. Remove chlorinated water

To remove the chlorinated water:

  1. Turn the pump circuit breaker on.
  2. Attach your hose to the faucet.
  3. Run the water to extract all the bleach for about 30 minutes to 24 hours. Remember to put the end of the hose to any landscape, bodies of water and septic system as the solution may damage them.

10. Test

Again, use chlorine papers to test whether there is still a bleach presence in the water coming out of your faucet or yard hydrant. Water heaters should be cleansed of chlorinated water.

To flush the bleach solution from the remainder of the water system, turn on all interior and external water taps and fixtures. To ensure that no bleach solution is present, use a chlorine test paper that reads 0 ppm of chlorine.

Key Takeaways

Having a household to manage is a severe undertaking. Like car maintenance, home renovation, and buying a new home appliance for a better and more efficient home experience, never forget to consider your water. 

Water both for bath and drinking should be free from contaminants. Therefore, it is essential to clean and disinfect your water wells. The safety and health of your family are your priority.

Here are some important points you learned from this post:

  • You can apply shock chlorination to your water well and household water systems
  • You should do it every 3 to 5 years
  • Be careful with the chemicals you mix 
  • Wear proper gear when shocking.

To ensure water safety, test your water once a year and regularly monitor and repair your water supply system. Good job, you are done reading this guide, we hope you are confident enough to do the shock chlorination process yourself.

However, if you are still hesitant to do so, never hesitate to call the experts. They would be much willing to help you with their expertise. 

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