How to Shock a Well Using Chlorine

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How to Shock a Well

The Shock chlorination procedure is the most common way of getting rid of home water system bacteria. Read on below to find out how to shock a well with Chlorine.

When to carry out the shocking process 

You should take the initiative of shock chlorinating as soon as you notice that there are harmful bacteria in your water or well system. There are four main ways to tell that your water system needs to be shock chlorinated.

Stained laundry

Stained laundry is one of the first signs that your water system is raided by bacteria. When your laundry gets in contact with bacteria, it is highly likely to turn into a pale orange color. Continuous exposure to bacteria is likely to ruin your laundry and so you need to treat your water system. 

Stained laundry can also be caused by rusty pipes, so it is important to determine the cause before you shock chlorinate your water system.

Blocked and clogged pipes

This is a common sign that your water system may be harboring bacteria. When your pipes are blocked up, your water tends to come out inconsistently. Bacteria can build up quickly on the sides of your pipes which then cause a clog in your water pipes, and this is what interferes with water flow, causing inconsistent flow and supply. 

To unblock your pipes, you therefore need to get rid of all the iron bacteria that has built up in your water system. Having bacteria in your water pipes is also a cause for alarm as bacteria in water can be a health hazard. Shocking a well is a suitable way to handle the situation and ensure the proper flow of water in your pipes. 


When you identify a slime substance growing in your water system, especially in your toilet tank, your system needs shock chlorinating. This may not be one of the first indications that there is bacteria in your water system but it is a factor you should check on. 

Slime growth happens when a bulk of iron bacteria congregates in one place. You can easily check whether there is slime in your toilet tank by removing the toilet tanks upper lid and peeking inside.

Bad smell in the water

When the water coming from your system has a foul smell, it is most likely because your system is contaminated with bacteria. Sulfate-reducing bacteria in your water system can cause the water to have a bad odor. 

As mentioned before, Iron bacteria builds up in the system and leads to the formation of slime. The sulfate-reducing bacteria then consumes the slime and the process creates a foul odor. The bad odor can make it unbearable and impossible for you to use your water. You can tackle the situation by shock chlorinating to clear the bacteria.

Septic Tank Issues

You should also consider shocking a well when there is a malfunctioning septic tank near your water system or house. It is highly likely for bacterial contamination to occur in your water system due to a malfunctioning septic system near you.

How to Shock a Well - Septic Tank Issues

Errors with System or well placement

Another reason to shock a well is when the pathway for surface water entry to the well is damaged, or located in the wrong place. An open well or damaged water system cover should also prompt shocking to ensure the water is free from bacteria. 

You should also shock chlorinate your well if there are any cracks in the grouting or faults in the overall construction. Shock Chlorination is one of the most recommended methods of cleaning and clearing the water system of bacteria.

Shock chlorinating should not be considered as a method of treating recurring water system bacteria issues. The best way to identify why the bacteria reoccurred is to hire a licensed well contractor to help solve the main issue. 

Dangers of Shock Chlorinating a well

Temporary arsenic release

The process of shock chlorinating is likely to increase the arsenic levels in your water. This mainly occurs in places where aquifer deposits have high arsenic levels. It is natural for arsenic to occur in States like Georgia that are located in the Southern Coastal Plain. Drinking water from various private wells in these States contain arsenic. 

The groundwater residues get exposed to oxygen when the water table is lowered from the pumping of the groundwater. Some of the arsenic in sediments can easily be dissolved because of oxygen. 

When you chlorinate your water system, there can be dissolving of arsenic from sediments and temporary release of it into the ground. This is made possible by the fact that chlorine is quite a strong oxidant. If your well contains levels of arsenic in water, consider the following:

  • Avoid using acid or alkaline bleach solution and preferably go for a solution with a PH of 6 or 7
  • Avoid leaving chlorine solutions in the well-casings longer than the prescribed 12 to 24 hours
  • Ensure you flush pipes, holding tanks, and well casings well to ensure all residual levels of chlorine are cleared.
  • Before drinking any well water, have it tested for arsenic once you have carried out shock chlorination. This helps to ensure that the concentration of arsenic is below 10 ppb, making the water safe for drinking.

Preparing for the shock chlorinating process

This process is used to clear bacterial contamination that may be in well water, well casings, the water supply system, and holding tanks. While this process can be carried out by a licensed well driller or contractor, you can also prepare for the shock chlorination process by following these considerations:

  • Highly concentrated chlorine solutions are dangerous. 

These solutions are highly corrosive and volatile making them dangerous to handle. When handling the concentrated chlorine solutions, you need to make sure you put on the right protective gear such as a protective apron, boots, rubber gloves, and goggles. You should also mix the solution in a place that is well ventilated.

  • High levels of chlorine in water after the shock chlorinating process. 

It is not advisable to drink your water immediately following the shock chlorination process as it leaves the water with high chlorine levels. You need to plan on having alternative drinking water and ensure that nobody, especially children, takes tap water during the treatment process.

  • Electric shock prevention. 

Be careful and turn off the pump circuit breaker before you remove the well cover or cap. This helps to prevent electric shock. You will later turn it back on and then off again before you replace the cover. 

In preventing shock, you can also put on rubber boots while carrying out chlorination.

  • Give chlorine adequate contact time to fight the existing bacteria. 

It is recommended for chlorine to take 12 to 24 hours in the system and nobody should use the water during the process.

  • Protection of water supply and treatment devices. 

When carrying out the procedure, devices such as filters, pressure tanks, and treatment devices can easily get damaged. It is therefore advisable to disconnect every carbon filter and have the osmosis units that are linked to your water lines reversed. 

It is highly likely for these filters to get damaged by the chlorine solution during the process. There are various water softeners, sand filters, and iron filters that however may not get damaged. You should also consult your device manufacturer before carrying out shocking for you to ensure you protect your water system equipment as required.

When is water ready for drinking after the shock chlorination process? 

No-one should consume tap water immediately after the process. You should wait for about two weeks and retest the water for bacteria. The water is safe to drink when the test results show no presence of coliform or E. coli bacteria. If the test results show the presence of any bacteria, you need to identify the main source of the bacteria and call a professional. Get help from a licensed well driller for a lasting solution.

Most appropriate chlorine bleach when shock chlorinating your water system

Your water system is a sensitive area and you need to therefore get everything right before you carry out the shock Chlorination procedure. Use plain, unscented chlorine bleach that is commonly used in homes and is also affordable. Avoid going for a fresh scent, lemon, or any chlorine products that are scented.

Chlorine is highly toxic and has a concentration of 200 milligrams in each liter or more. Shocking your water supply system entails adding a solution of chlorine to the water system or well until the concentration level gets to 200 milligrams for each liter. The solution in the water is then circulated to clean out bacteria in all parts of the system.

You will find chlorine in different forms and liquid household bleach and dry chlorine are the most preferred for disinfecting a well. There is 65 percent of calcium hypochlorite in dry chlorine while bleach has nearly 5.25 percent of sodium hypochlorite. 

When these two are appropriately used, they disinfect wells or water systems effectively. Remember to avoid using bleach that has a scent as any additives in the solution may contain chemicals that could be dangerous for animal or human consumption.

How much chlorine should you use?

If you intend to shock a well using laundry bleach, use 3 pints for every 100 gallons of water in the water system or well. You may be wondering how to determine the amount of water in a well. The following steps will help you.

  • The distance from the bottom of the well to where the water has reached will help in determining the depth of the water in the well. Measure the distance to the water level and subtract it from the depth of the well and this gives you the depth of the water you want to disinfect. 
  • You can also contact the professional drilling company that drilled your well for clarification on the depth of your well if you are not certain. Professional well-drillers often keep customer records for future reference. A different licensed well-driller could also help you to find out the depth of your well. You simply need to reach and request a service.
  • Using the diameter of your well, determine the storage of the well per each foot of water. There are two kinds of wells; bored and drilled wells. The diameter on the inside for every drilled well casing ranges from 4 to 10 inches. A bored well on the other hand has a larger diameter ranging from 12 to 36 inches. Use this information to determine the storage of the water per foot and this helps you know the amount of chlorine to use while shocking a well.
  • You can also contact a professional well driller or your local extension office to help you in finding out the diameter of your well. The total depth of water that you find should be multiplied by the storage of the water per foot. As earlier mentioned, put 3 pints of regular bleach for every 100 gallons of water in the well or water system. [1]
  • You should then add 3 pints for treating the system including the pipes, water heater, and pressure tank. If for instance, the well contains 300 gallons of water, add 9 pints of bleach for treating the well and an additional 3 pints for treating the household plumbing. If you are not certain about the depth of the water, the volume of the bleach should be the same as two times the one used for a water depth of 150 ft.

The measurements should be made keenly because water is delicate and the substances used may be toxic for human or animal consumption. Using too much bleach will make the water unusable for a longer period of time and will then require more flushing of your water system before it is suitable for use. 

How to Shock a Well using these steps

How to Shock a Well

This process does not require much professional expertise and with simple guidelines, you can do it yourself. The process follows various steps to fight bacteria in wells or water systems.

1. Cleaning

Begin by cleaning the well-area from any unnecessary objects or wreckages. Clean the storage tank, spring house, and well house too. You should then turn off the pump circuit breaker to avoid electric shock before removing the well cover. 

Use an appropriate chlorine solution to clean the interior surface that is in your reach and do it well. If the well-cap is not in good condition, now is the time to fix or replace it as loose caps may lead to more exposure to bacteria.

2. Calculating and adding

When you have the required water level measurements, pour 3 pints of chlorine bleach for every 100 gallons of water as discussed previously. Proceed to add 3 pints for disinfecting the system devices.

3. Mixing

Mixing the chlorine solution requires having a clean device such as a garden hose that you attach near and inside the well. Have the outdoor faucet turned and keep turning the pump allowing the water to run until there is a chlorine smell coming from the garden hose. Use the garden hose to clean inside the well-casing for approximately 20 minutes before turning off the faucet.

4. Circulating

While shock chlorinating your well, you need to let the solution circulate properly in the entire water system. Keep every faucet open beginning from the outside and then from the inside and allow the water to flow. 

When you finally smell a strong chlorine odor from the toilet and faucet, close every faucet and begin to flush the toilets one at a time. After the flushing, you can add 3 pints of bleach into the well if you lose the strong chlorine smell. Do that and try flushing again.

5. Flushing and completion

Turn off the pump circuit breaker and put the well cover back in place. You should leave the chlorinated water in the system or well for a period of 12 to 24 hours and then turn on the pump circuit breaker. Turn on the outside faucets one after the other to clear out any chlorine left in the system. Let the faucets run until there is no longer any chlorine odor from the system. 

Proceed to flush every toilet as you complete the shocking process. It is important to avoid running more than 100 gallons of chlorinated water into your water system and ensure that your water is well conserved.


The well chlorinating process is not complex and is known to be an effective way of removing bacteria from your well or water system. This is unless the bacteria reoccurs which may then signal a need for professional help.

The H2Home Lab team is dedicated to helping you find the best solutions to your specific water needs, as well as provide troubleshooting tips and guides for water filtration, heating, softening and plumbing. We hope you will find the info you need on our site from any one of our buying guides or subject matter articles.

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