- If runoff water from the storm gets into the septic tank, it will get full and since the soil in the leachfield will be already too saturated, the water will start backing up into the house or from the manhole. Maintaining the septic system BEFORE the heavy rains
Will shocking a well damage a septic system?
High loads of chlorine in the septic tank can kill beneficial bacteria and make it necessary to re-inoculate the septic system. But do not let the chlorinated water run onto lawns, gardens or other plants because chlorine can injure them.
Does chlorinated water hurt septic system?
At homes where the water supply is not potable due to bacterial contamination, a common temporary solution is the installation of a chlorinator. In a properly-operating chlorinator the level of chlorine in the house drinking water will not harm the septic system.
How long does it take for water to clear after shocking a well?
It will usually take 4 to 8 hours to flush the well after a standard well chlorination. The water may become discolored during flushing because the chlorine may have loosened the hard water deposits in the plumbing. Caution: The chlorine must be completely flushed from plumbing system.
How long does it take for chlorine to dissipate from a well?
It can take 30 minutes to 24 hours or more to flush all of the chlorine from the well. ►Once the chlorine is gone from the well, open up each fixture one at a time until the chlorine smell is no longer present. This will purge the remaining chlorine from the water system.
What happens when you shock a well?
Shock chlorination is a disinfection treatment recommended when a domestic drinking water system is contaminated with bacteria. Contamination can occur when the well is installed or when repairs are made to the pump or plumbing. Shock chlorination introduces very high levels of chlorine into a water system.
Is it safe to shock a well?
Although shock chlorination will sanitize wells, it may temporarily increase the arsenic levels of water in areas where aquifer sediments contain high levels of arsenic (WDNR, 2008).
What will ruin a septic system?
Any paper products like tissues, paper towels, tampons, or sanitary products, even some heavier toilet paper, will clog your system if you flush enough of it. Wet wipes are another product that you should never flush into a septic system.
Can you put bleach in septic tank?
You might consider bleach to be a great cleaner to use for your septic system. Unfortunately, that mindset is a dangerous one to have because it’s usually recommended to avoid using bleach in your septic system. The chemicals within bleach can kill the bacteria that your septic tank relies on.
How much chlorine can a septic system handle?
Moderate use of bleach will not throw your septic system out of balance. Moderate use is the amount used in one normal size load of laundry ( 3/4 cup ) or the amount used in an application of toilet bowl cleaner.
How much does it cost to shock a well?
The cost ranges from $80 – $200. You can also perform the task yourself. It simply consists of pouring diluted chlorine into the water, letting it sit for a while, and then flushing the chlorine out of the system. You do this by making preparations, adding the chlorine bleach, and disinfecting the well.
What does it mean when your well water turns brown?
Iron and manganese, rust, silt, tannins, and the well itself can be the cause why well water suddenly turns brown. While water discoloration can be a problem, there is no need to immediately hire the services of a plumber. It can be contaminated with rust which causes it to turn brown.
Should you pour bleach in a well?
Bleach should not be put into the well straight from the bottle. The general recommendation is to dilute the laundry bleach 1:100, (one gallon of bleach to 100 gallons or water; half a gallon of bleach to 50 gallons of water; a quart of bleach to 25 gallons of water.)
How do you flush chlorine out of a well?
Use ordinary liquid laundry bleach to shock chlorinate the water system. Determine how much bleach to use, then pour the bleach down the well and circulate it through the whole water distribution system. Wait 6-12 hours for the chlorine to work, then flush the chlorinated water from your well and pipes.
How often should you chlorinate a well?
Homeowners with private wells should have their well water tested every 3 to 5 years for some contaminants, including bacteria. If these tests turn up positive for bacteria, chlorinating the well may be a way to resolve the problem.
Shock Chlorination of Wells – Should I shock my well?
Our work has a positive impact on the lives of Texans as well as the state’s economy. View Economic Impacts» for further information. By Mark L. McFarland, Associate Professor and Extension Soil Fertility Specialist at the University of California, Davis Assistant Professor and Extension Specialist For Water Resources for the Texas A&M University System, Monty C. Dozier Professor Craig Runyan of the Extension Plant Sciences Department at New Mexico State University is a program coordinator. Shock chlorination is a method of cleaning a water well that is used in agriculture.
Contamination can occur during the installation of the well, during the maintenance of the pump or the piping, or when rainwater enters the well via the opening.
Continuous chlorination (or the use of another continuous disinfection technology) will be required in that circumstance in order to ensure the safety of the water supply.
During the disinfection process, the water from the system is not fit for consumption, and neither people nor animals should be exposed to it for an extended period of time.
As a precaution, if there is an automated watering system for animals or irrigation, a secondary water supply should be provided throughout the treatment time.
Water filters, such as carbon filters, should be temporarily detached or bypassed during shock chlorination to avoid contamination of drinking water.
Activated carbon filters left in place during the chlorination process will actually remove the chlorine until they get overloaded.
Chlorine Sources
Chelating agents such as chlorine are very harmful to bacteria at concentrations of 200 milligrams per liter or higher. Adding a chlorine solution to the water supply until the water has reached a concentration of 200 milligrams per liter and then circulating the water to disinfect all elements of the water system is called shock chlorination. In addition to the liquid form, chlorine is also available in powder form. Dry chlorine and liquid home bleach are the two most often used disinfectants for wells, respectively.
When used appropriately, they are just as effective at disinfecting wells as they are at cleaning them. You should avoid using bleach that has a “fresh aroma,” a lemon fragrance, or any other additions since it may include chemicals that are harmful to humans and animals when consumed.
Chlorination Procedure
The quantity of chlorine that is required is decided by the amount of water that is currently present in the well. To find out the depth of your water well and the amount of static water in your well, contact the business that built it. The depth of standing water in the well will be equal to the depth of the well minus the static water level. The standing water depth of a water well that is 110 feet deep and has a static water level of 90 feet would be 20 feet (110 feet – 90 feet = 20 feet) in this example.
Use a volume of bleach equal to two times the depth value for the suitable casing diameter if the standing water depth of the water in the well is not known.
More bleach than suggested is not required and will result in further flushing before the water can be used.
Powdered and tablet forms of high-test hypochlorite are both available.
- The first step is to empty the system of as much water as possible. It is possible that the chlorine solution will cause damage to the rubber air-water separator in the pressure tank if the system includes a pressure tank with a bladder. It is recommended that you consult your manufacturer’s handbook to determine if the pressure tank should be bypassed. Alternatively, if the pressure tank lacks a bladder, the air should be released to enable for the tank to be filled with chlorinated water. Drain any hot water heaters as well, to enable chlorinated water to flow through the hot water system, and Removing the plug or screen from the well cap allows you to have access to the inside of the well casing and inspect it. Place the proper amount of liquid bleach (see Table 1) in a 5-gallon bucket and fill the bucket halfway with clean water to dilute the bleach. You should use dry chlorine in a 5-gallon bucket filled with clean water to dissolve the bleach if you are using it. The amount to use is determined by table 2. Placing a funnel in the access hole of the well and pouring solution along the walls of the well casing are recommended. Fill the well with water by attaching the garden hose to a nearby faucet and running it through a funnel in the well’s access hole to flush out the inside of the well. Continue the washing procedure for another 10 minutes, checking to see whether there is a strong chlorine scent. Repeatedly start and stop the well pump will help to properly mix the chlorine into the well water. After 2 hours, open the faucet closest to your well and let it flow until a strong odor of chlorine is noticed. Then close the faucet and turn off the well pump again. Continue to the next faucet and repeat the process. Continually run the faucets until chlorine can be detected in all of them. If the odor is not detected, check the chlorine rate from Table 1 or Table 2 and add more chlorine to the well, repeating steps one through four
- If the odor is still not detected, repeat steps one through four
- Discontinue operation of the water system for at least 12 hours, and ideally 24 hours
- After that, flush the system to remove any lingering chlorine. Starting with exterior faucets, turn them on and let them running for a few minutes until the chlorine smell has dissipated. Allowing the water to run on the ground will help to minimize the strain on your septic system and save money. High concentrations of chlorine in the septic tank might destroy beneficial bacteria, necessitating the need to re-inoculate the septic system. However, do not let the chlorinated water to spill onto lawns, gardens, or other plants, since chlorine may be harmful to these types of plants. The garden hose should be directed to a field or low-lying region where it will not be in contact with desired plants. Caution should be exercised when discharging chlorinated water directly into bodies of water like ponds, lakes, rivers, or streams. Turn on the interior faucets until the system is thoroughly flushed, and then turn them off. Make sure to get the well water tested again for bacterial contamination after it has been chlorinated. If bacteria are still identified in the well water, the chlorination procedure should be repeated, and the water should be tested again. After the third detection of bacterial contamination, look for probable causes of reinfection, such as
- A poorly built wellhead, or the presence of animal enclosures or septic tanks in close proximity to the wellhead
It may be essential to build a continuous chlorination system or another type of continuous disinfection system in order to meet the requirements. The Tex-A-Syst rural water well assessment publications (B-6023 through B-6032), which are available through Texas Cooperative Extension, include more information on wellhead protection and are available for purchase. Download a printer-friendly version of this publication by clicking on the following link: Wells are subjected to a shock chlorination procedure.
Make contact with the appropriate county office.
Disinfecting Your Well Water: Shock Chlorination
Uttam Saha, Leticia Sonon, Pamela Turner, and David Kissel collaborated on the revision. Jorge H. Atiles and Paul F. Vendrell wrote the original draft for this piece.
- What is Shock Chlorination
- When should Shock Chlorination be used
- And is Shock Chlorination always effective are all questions that need to be answered. Temporary Arsenic Release after Shock Chlorination When it comes to shock chlorination, what precautions should be taken are: Once the water has been treated with shock chlorination, when will it be drinkable again? It is important to know what type of chlorine bleach should be used. What amount of chlorine should I use
- The Shock Chlorination Process is a method of disinfection.
Shock chlorination is a basic procedure for cleaning your water system. The following are recommendations for utilizing this therapy in a safe and effective manner.
What is Shock Chlorination?
Water systems such as wells, springs, and cisterns are disinfected by shock chlorination, which is accomplished by utilizing household liquid bleach to disinfect the water (or chlorine). Treatment of bacterial contamination in residential water systems using shock chlorination is the most generally recommended method of disinfection today.
When Should Shock Chlorination Be Used?
It is advised to use shock chlorination:
- When a new well is completed or an unused well is returned to service
- When annual water test results indicate the presence of bacteria
- Whenever a well system is opened for any installation, repair, or maintenance
- Whenever the well is surrounded by flood waters (standing water around or covering the well casing)
- Whenever well water becomes muddy or cloudy after a rain
- Whenever the well has iron bacteria or sulfur-reducing bacteria symptoms such as slime (biofilm) or odor
- Whenever the well is surrounded by flood waters (standing
Is Shock Chlorination Always Effective?
In the event that a source of bacterial contamination survives after shock chlorination, bacterial contamination may return. For example,
- A local septic system that is not operating properly
- A channel for surface water to enter a well, such as:
- The inappropriate placement of a well
- The lack of a well cap
- Or the wrong placement or looseness of a well cap when there is insufficient grouting or other flaws during the well building a well casing that has fractured
Using shock chlorination to address reoccurring bacteria issues is not advised in most cases.
A licensed well driller/contractor should be enlisted to locate and eradicate the source(s) of the pollution. The installation of a continuous disinfecting treatment system is still another alternative.
Shock Chlorination and Temporary Arsenic Release
Aquifer sediments with high amounts of arsenic may temporarily raise the arsenic levels in water, despite the fact that shock chlorination will disinfect the wells (WDNR, 2008). It has been shown that arsenic occurs naturally in some bedrock and aquifer sediments in the southern coastal plain (SCP) area of Georgia, and it has also been discovered in drinking water from several private wells in the region. As a result of groundwater pumping, the water table is reduced, allowing oxygen to reach sediments in the groundwater below the water table.
In a similar vein, because chlorine is an extremely powerful oxidant, it has the potential to breakdown arsenic from sediments and release it into groundwater.
- Neither an acidic nor an alkaline bleach solution should be used. The ideal solution has a pH of 6-7. Avoid leaving chlorine solutions in well casings for longer periods of time than recommended (12-24 hours). To ensure that there are no residual chlorine levels in well casings, holding tanks, and pipelines, complete flushing should be performed. After shock chlorination, well water used for drinking should be tested for arsenic to ensure that the arsenic content is below a safe limit (less than 10 parts per billion).
What Precautions Should Be Taken Prior to Shock Chlorination?
It is necessary to utilize shock chlorination to eliminate bacterial pollutants from well water, well casings, holding tanks, and the whole water distribution system. A well driller who holds a valid license has received shock chlorinate training. Make careful to follow these safety precautions if you want to shock chlorinate your own well:
- The use of concentrated chlorine solutions for shock chlorination can be hazardous to the environment. In order to protect oneself from the volatile and corrosive properties of the concentrated chlorine solution, one should dress in protective clothes such as goggles, an apron, rubber gloves, and boots. In a well-ventilated location, combine and add the chlorine solution. After shock chlorination, the chlorine levels in the water are quite high. Make arrangements for a different supply of drinking water if necessary. Make sure that children and elderly individuals do not drink tap water while the water is being treated
- Chlorine should have enough contact time with the germs to destroy them. Take precautions to ensure that no one in your household uses the water for any reason throughout the 12 to 24 hour treatment period
- Keeping the water pump from delivering an electric shock. Prior to removing the well cap or cover, be sure that the pump circuit breaker has been turned off. To complete Step 3 of this shock chlorination procedure, you will need to reconnect the electricity, but make sure to turn the pump circuit breaker off again before reinstalling the well cap or cover (Step 6). Wearing water-resistant rubber boots is recommended for protecting the components of water supply and treatment systems. Shock chlorinating a water supply system has the potential to cause damage to components such as pressure tanks, certain filters and filter media, and various treatment devices, among other components. Before you begin, make sure that all carbon filters and reverse osmosis devices that are connected to your household water pipes have been disconnected. The high concentration of chlorine in the solution can harm these filters. Some water softeners, iron filters, and sand filters, on the other hand, may not be affected. Before shocking chlorinating your water supply system, consult with component makers to learn how to bypass or safeguard this equipment, if required.
When Will the Water Be Drinkable Again after Shock Chlorination?
Retesting for total coliform and E. coli bacteria should be done one to two weeks after the shock chlorination of the water supply system has been completed. Follow the instructions for sample collection to the letter. If the results of the test demonstrate that there are no coliform bacteria present, the water is safe to drink. When coliform bacteria are detected, the source(s) of contamination should be located and eradicated by a licensed well driller/contractor, or a continuous disinfection treatment system should be established to ensure that the bacteria are not present in the water supply.
What Kind of Chlorine Bleach Should Be Used?
Use the ordinary (and, in most cases, least costly) unscented home chlorine bleach containing at least 5 percent sodium hypochlorite that can be bought in supermarkets; do not purchase scented chlorine products such as fresh smell, lemon, or other citrus scents.
How Much Chlorine Do I Use?
Adding 3 quarts of common laundry bleach to every 100 gallons of water in the well is recommended when using this product. In order to assess how much standing water is in your well, follow the methods outlined below:
- Calculate the depth of water in your well, which is the distance between the bottom of the well and the water level at the surface of the water. Measure the distance between the ground level and the water level in order to obtain this information (distance “b” in the diagram). To get the entire depth of the water, subtract the well depth “a” from the total depth of the water: a – b = c. If you are unsure about the depth of your well, but you are familiar with the well drilling business that built it, you should call that company. Well drillers frequently maintain detailed records of all of the wells they drill. If you are unable to locate any records pertaining to your well, you should call a qualified well driller who can assist you in obtaining the necessary measurements. Calculate the amount of water that can be stored in your well per foot of water. The diameter of your well is used to get this value. Wells are generally classified into two types: drilled wells and bored wells. The interior diameter of a drilled well’s casing (well pipe) is normally between 4 and 10 inches in diameter. Bored wells are greater in size, with diameters ranging from 12 to 36 inches. To find out how much water your well can hold per foot of water, use the following table:
| Drilled Well/Pipe | Bored Well | ||
| Diameter (inches) | Storage per footof water (gal/ft)* | Diameter (inches) | Storage per footof water (gal/ft) |
| 4″ | 0.653 | 12″ | 5.88 |
| 5″ | 1.02 | 16″ | 10.5 |
| 6″ | 1.47 | 20″ | 16.3 |
| 7″ | 2.00 | 24″ | 23.5 |
| 8″ | 2.61 | 28″ | 32.0 |
| 9″ | 3.30 | 32″ | 41.8 |
| 10″ | 4.08 | 36″ | 52.9 |
| * If your well diameter is not listed in the above table, or if you use a cistern or reservoir, you will need to contact your local Extension office for more information. |
- Multiply your entire depth of water “c” by your storage per foot of water “s.” This is your storage per foot of water. This example will make the assumption that “c” is 204 feet in length. The quantity of water in your well will be the final product: 204 divided by 1.47 equals 300 gal. 3 pints of bleach per 100 gallons of water should be poured into your well, with an additional 3 pints to treat the domestic plumbing, which includes the pressure tank, the hot water heater, and the pipes. Using the following example, if the volume of water in your well is 300 gallons, you will add 9 pints of bleach to treat the well and 3 more pints to treat the plumbing, for a total of 12 pints or 1.5 gallons:
Use a volume of bleach equal to two times the 150-foot water depth for the suitable casing diameter if the water depth in the well cannot be determined. For example, a casing with an 8-inch diameter and a 150-foot water depth would take 1.85 gallons of ordinary home bleach. If the depth of the water is not determined, the amount of bleach necessary will be 1.85 x 2 = 3.7 gallons of bleach. Do not use more bleach than the prescribed amount since it is not essential and will result in further flushing before using the bleach in the home or on the clothes.
The Shock Chlorination Process
- CLEANING: Remove any loose or foreign material from the well house, spring house, or storage tank before starting. Removing the well cap or lid will allow you to safely turn off the pump circuit breaker. Then use a strong chlorine solution (1/2 gallon chlorine bleach per 5 gallons clean water) to cleanse the interior surfaces that are easily accessible. To avoid recontamination, the well must be equipped with a sanitary cover that is in excellent working order
- Otherwise, the well must be abandoned. CALCULATING AND DISPENSING: Pour 3 pints of chlorine bleach per 100 gallons of water, plus an additional 3 pints, into your well, following the directions outlined before. MIX: Attach a clean garden hose to the outside faucet closest to the well and insert the other end of the hose into the well to make a mixing bowl. After turning on the faucet, re-starting the pump, and allowing the water to flow until you smell chlorine coming out of the hose, turn off the faucet. Close the exterior faucet after washing down the interior of the well casing with the hose for approximately 15 minutes. Allow the solution to circulate throughout the system by pressing the button. Open each faucet, starting outdoors and working your way inside (both hot and cold), one at a time, and allow the water to flow freely. When a strong chlorine stench is noticed, turn off all of the faucets. Flush the toilets one at a time until they are completely empty. The well should be filled with an extra 3 quarts of bleach and tested again. If a strong chlorine odor cannot be detected at each faucet and toilet, repeat the process. TO COMPLETE THE FLUSH AND FINISH, turn off the pump circuit breaker, replace the well cap or cover, and flush and finish again. It is recommended that chlorinated water be left in the system for 12 to 24 hours. Turn on the circuit breaker for the pump. Remove any residual chlorine from the system by turning on exterior faucets one at a time and allowing them to run until there is no longer any chlorine odor in the air. To finish, turn on each of the interior faucets one at a time until the water is clear and the chlorine smell has disappeared. Each toilet should be flushed. More than 100 gallons of chlorinated water should not be discharged into your septic system, nor should the water be allowed to drain into a stream, pond, or lake through an open drainage ditch. Alternatively, you might run the water into a storage tank and utilize it to irrigate vegetation once the chlorine has dissipated
- This would help to preserve water.
Sources
A report published by the University of Georgia Cooperative Extension on “Shock Chlorination of Home Wells, Springs, and Cisterns.” A report by the Cooperative Extension Service at the University of Nebraska-Lincoln on “Shock Chlorination of Domestic Water Supplies.” Shock chlorination is used to disinfect private household water supply systems as part of the Virginia Household Water Quality Program.
Virginia Cooperative Extension, Virginia Polytechnic Institute and State University are three of the state’s educational institutions.
Washington Department of Natural Resources (WDNR). Arsenic Sensitive Areas should have enough chlorination. Wisconsin Department of Natural Resources Publication No. PUB-DG-069 2002
Reviewers
Adam Speir (UGA), Alyson McCann (University of Rhode Island), Jackie Ogden (UGA), and Mark Risse are among others who have contributed to this work (UGA) History of the current status and revisions Originally published on December 17, 2012. On September 1st, 2016, the full review was published.
Shock Chlorination
To shock chlorinate the water supply, use a regular liquid laundry bleach solution. Determining the appropriate amount of bleach to use, pouring it down the well and allowing it to circulate throughout the entire water distribution system. To remove chlorinated water from your well and pipes, wait 6-12 hours for the chlorine to take effect before flushing them. After 2-3 days, take another sample of the water.
Step-by-Step Instructions
Shock Chlorination Procedure with Step-by-Step Instructions
1 Create an opening
Make an aperture at the top of the well so that the chlorine solution can be poured in. Because well caps differ from one another, this phase may be more difficult for certain wells than others.
- If there is a flat or domed cap on top of a well that does not have any pipes going out of it, you can unbolt the cap and take it off
- Please do not remove the bolts if pipes are protruding from the well cap! The bolts hold the bottom plate of the seal in place, and if the bolts are removed, the bottom plate will fall into your well. As a result, there may be some weight on the cap, and removing the lid may result in the loss of your pump at the bottom of the well. The vent pipe hole is the most suitable alternative. The hole in the cap may be used to pour the chlorine solution down if you can get your hands on this little bit of pipe that sticks up out of the cap. Call a well or pump technician for assistance if you are having trouble with this step
2 Determine amount of bleach
Calculate the amount of bleach that will be required. It is advised that an initial chlorine dosage of 50 to 100 parts per million (ppm) be used. To determine how much bleach to use for this concentration, refer to the table below, which takes into account the diameter of the well and the depth of water in the well. Keep in mind that the depth of water is not the overall depth of the well; rather, it is the distance between the water level and the bottom of the well. This information may be found on your well’s logbook.
This information may also be available from your well driller.
Amount of Ordinary Chlorine Laundry Bleach Needed to Shock a Well(roughly 100 ppm)
The depth of the water in the well (feet) The diameter of the well (in) 150 feet or less than 50 feet, 50 feet to 100 feet, 100 feet to 150 feet, or higher than 150 feet a cup of twenty-one a cup a cup a cup a cup a cup a cup a cup a cup a cup a cup a cup a cup a cup a cup a cup a cup a cup a cup 1 cup of oats 41 cup (in liters) 2 cups of coffee 3 cups of coffee 4 cups of coffee (1 quart) 62 cups of coffee 4 cups of coffee (1 quart) 6 cups (about 1 1/2 quarts) a total of eight cups (2 quarts) 84 cups of coffee (1 quart) a total of eight cups (2 quarts) a total of eight cups (2 quarts) 12 cups of coffee (3 quarts) 108 cups of coffee (2 quarts) 12 cups of coffee (3 quarts) 12 cups of coffee (3 quarts) 1 gallon (16 cups) 4 quarts (1 gallon) a total of 128 cups (2 quarts) 12 cups of coffee (3 quarts) 1 gallon (16 cups) 4 quarts (1 gallon) 1 gallon (16 cups) 4 quarts (1 gallon)
3 Right type of chlorine bleach
Check to verify that you have the proper type of chlorine bleach. Make use of regular liquid laundry bleach (Chlorox, Purex, or a generic brand). Use of bleach containing chemicals or unique smells is not recommended. The sodium hypochlorite should be listed on the label, and the concentration should be between 5 and 6 percent.
4 Dilute the bleach
Use no more than 2 cups of sugar per 2 gallon pail of water. Straight chlorine has the potential to damage metal well components.
5 Pour the diluted bleach
Pour the diluted chlorine bleach solution down the well.
It should be clear. Take care not to get water on your clothes or skin.
6 Mix
Combine the chlorine and well water in a large mixing bowl. Water should be turned on by attaching a hose to a faucet close to the well. After you detect the presence of chlorine, guide the water from the hose back down into the top of the well (if you do not detect the presence of chlorine after a few minutes, add more before rotating the water).
7 check if chlorinated
Opening each fixture (sink, shower, outdoor faucet, etc.) one at a time and allowing the water to flow until you smell chlorine will ensure that the system has been chlorinated properly. Run hot water to pull chlorine into the water heater, and then turn off the water. If you do not detect any chlorine, add extra diluted bleach solution and swirl the water with the hose once more.
8 Hold chlorine in pipes
Do not use the water for 6-12 hours after the chlorine has been added to the pipes. (A few of toilet flushes are OK.)
9 Remove chlorinated water
Removing chlorinated water from the well and pipelines is essential. Run a hose outside until you no longer detect the odor of chlorine. This water should not be used on plants. After that, drain the chlorinated water from the plumbing system. It is better for the septic tank if you flush less water down the drain.
10 Test
Coliform bacteria should be tested 3 days after the initial test. Drinking the water until you obtain “clean” test results is not recommended. Gail Andrews of the Ohio State University Extension Service prepared this document in February 2002.
Disinfecting a Domestic Well with Shock Chlorination
Marsha Wright is a Water Quality and Pesticides Specialist with the University of Illinois Extension. New Mexico State University’s College of Agriculture, Consumer, and Environmental Sciences is home to a diverse range of students. (PDF that is easy to print) In the event that a home drinking water supply is polluted with microorganisms, shock chlorination is a disinfection procedure that should be considered. Contamination can occur during the installation of the well, as well as during the maintenance of the pump or the piping.
- If the bacteria in the groundwater is the root of the problem, the system will become polluted once more when the water is pumped into the plumbing system.
- Water systems are subjected to shock chlorination, which delivers extremely high quantities of chlorine into the system.
- Plan to disinfect the faucets and toilets when they will not be in use for at least 8 hours, and ideally 12 to 24 hours, before beginning the process.
- When it comes to mechanical water systems for animals and irrigation, extra considerations must be taken.
- To prevent harm to landscaping plants and grass areas, chlorinated water discharged out of a sprinkler or drip system should be directed away from the plants.
- During shock chlorination, some water filters, such as carbon filters, should be temporarily unplugged or bypassed to ensure proper operation.
- For the disinfection procedure, use liquid home bleach containing 5.25 percent chlorine, according to the manufacturer.
- One gallon of bleach will treat up to an 8-inch diameter well with a 100-foot depth of water in one treatment.
- Direct skin contact with bleach solutions should be avoided.
If you accidently get it on your skin, rinse it away with plenty of clean water right away. Never combine chlorine bleach with other cleansers since it might result in the production of a poisonous gas.
Disinfection Procedure
- Pour 2 quarts of bleach into 10 gallons of water and pour into a well to dissolve the bleach. Connect a garden hose to a nearby faucet and use it to thoroughly clean the inside of the well. Open each faucet and let the water to flow until a strong chlorine stench is noticed, then turn the faucet off and move on to the next one in the series of steps. Remember to include outside faucets and fire hydrants. Using chlorinated water, flush the water heater and allow it to recharge. If a strong odor is not detected at all outputs, the well may require more chlorine. To detect chlorine at each outlet, utilize chlorine test strips that are available with swimming pool supplies if you have impaired sense of smell. Make a thorough cleaning of the toilets. Add an extra 2 quarts of bleach to 10 gallons of water and mix thoroughly. It should be poured into the well without being pumped
- Make sure to let the chlorinated water sit in the well and pipes for at least 8 hours (ideally 12 to 24 hours). Continue to direct water from outside faucets to the garbage disposal (away from desirable plants) until the chlorine odor is just barely detectable or not detectable at any of the faucets. Then turn on all of the inside faucets until there is no more chlorine smell. Reduce the amount of chlorinated water entering a septic tank as much as possible.
Some chlorine may remain in the system for up to seven to ten days. Water with a little chlorine odor should be suitable for the majority of applications. If the chlorine odor or taste bothers you, simply leave the water running until the chlorine fades completely. After cleansing the system, take a sample of the water (in accordance with laboratory instructions) and have it tested for biological contamination around 2 weeks after flushing. It is recommended that you repeat the test in 2 to 3 months to ensure that the system has not been poisoned again.
Because human and animal waste are typical sources of bacterial contamination, it’s possible that a nearby septic system or livestock cage is to blame for the contamination.
As soon as you detect a change in the taste or smell of your water, or if you observe an increase in the number of unexplained illnesses in your family, test the water.
(Farmstead Assessment System).
References
Wanda Eubank, Jerry D. Carpenter, Beverly A. Maltsberger, and Nix Anderson are among those who have contributed to this work. Bacteria in Drinking Water, WQ0102, University Extension, University of Missouri-Columbia. Bacteria in Drinking Water, WQ0102, University Extension, University of Missouri-Columbia. Karen Mancl’s Bacteria in Drinking Water was published by The Ohio State University. Linda Wagenet and Ann Lemley are co-authors of this work. Chlorination of Drinking Water, Cornell Cooperative Extension, Cornell University Fact Sheet 5, Cornell Cooperative Extension, Cornell University.
How to Shock Chlorination, Shock Disinfect Your Private Water Supply, or Water Well Shock Chlorinate (Chlorine Disinfection)
For the detection of total Coliform Bacteria, an enumeration (count the colonies) test method is used. Individuals or families that use private water sources are responsible for testing the water for pollution, as opposed to public water supplies, which are tested on a regular basis to guarantee the water is safe to drink. Shock chlorination or disinfection is the most generally recommended approach for first treatment if test results show that bacterial contamination has occurred. It is the one-time delivery of a powerful chlorine solution into the whole water distribution system that is known as shock chlorination (disinfection) (well, pump, distribution pipeline, etc.).
When to Shock Disinfect the Well
It is advised to use shock chlorination (disinfection):
- The presence of Bacteria is indicated by laboratory findings
- Following the construction of a new well or the replacement or repair of a pump
- It is necessary to close the distribution system for repairs or maintenance, or if it has not been utilized on a regular basis, such as on a weekly basis.
- Following a floodwater contamination occurrence, a contamination incident, or damage to the system
- For the treatment of Iron, Slime, and Sulfate-reducing Bacteria, and for the reduction of other nuisance concerns such as discolored water, excessive iron and manganese concentrations, turbidity, and black water, as well as smells
In these instances, shock chlorination (disinfection) is suggested in order to guarantee that any bacterial contamination is effectively controlled.
How to Shock Disinfect a Well Safely
Fill a five-gallon container halfway with new water before starting the shock chlorination procedure. If strong chlorine accidently gets into contact with your eyes or skin, flush the afflicted area with this fresh water for 10-15 minutes to remove the chlorine. Immediately seek medical attention if you get any of the chlorine solutions into your eyes after thoroughly flushing the damaged eye. A second safety tip is to ensure that you are wearing the proper protective gear and equipment. Wearing goggles will help to keep the chlorine substance and your eyes from coming into touch.
Wearing a waterproof suit, coveralls, or a full-length apron will help to keep your clothes from being discolored.
Avoid bathing, drinking, washing clothes or dishes, or doing any other potable or hygienic tasks while the Shock Disinfection procedure is in progress. Instead, utilize the water for other purposes. Don’t even think of using the water to irrigate your yard or your crops!
Preparations
Start the shock chlorination (disinfection) method by performing the following steps:
- Ensuring that the well structure is sufficient to prevent direct entrance of pollutants
- And
- Find any visible sources of possible contamination and eliminate them, such as a badly placed well cap, a well that is below grade, or a well with broken casing or a leaking pitless adapter
- If you are replacing a pump, pipe, or electric cables, be certain that the components are disinfected before inserting them in the well.
- Isolating components of the system that may be harmed by the high concentration of chlorine, such as a carbon filter, a water softener, and a large number of reverse osmosis treatment units. We highly recommend that you use Well-Safe Sanitizer while doing a shock disinfection.
The most effective method of preventing a water supply from becoming polluted by bacteria or diseases is to prevent the bacteria from gaining access to the water source in question. If the water source is a pond, spring, or other body of surface water, it is difficult to keep pollutants from getting into the water delivery system. Some cracks in well pits, spring houses (or spring boxes), and other possible sites of entry can be sealed with caulk, which is effective in some situations. Make certain that all debris (leaves, twigs, and so on) is removed from the spring house, well pit, and storage reservoir.
Well Chlorination (Disinfection):
Using a chlorine-based chemical to mix with well water in sufficient amounts to form a solution that contains 200 milligrams per liter (mg/l), or parts per million (ppm), of chlorine across the whole system is referred to as shock chlorination or shock disinfection of the well (well, distribution pipeline, water heater, pressure tank, and other equipment). It’s important to remember that chlorine is extremely volatile, making it risky to deal with in tight spaces. Make certain that the work environment is well-ventilated.
Follow these steps to disinfect the well pit, spring house, or other elements of the distribution equipment that may add bacteria to the water supply (such as the pump, motor, pressure tank, and exposed wiring conduits) before using the water: Drain as much water as you possibly can from the system.
When determining whether or not the pressure tank should be bypassed, refer to the manufacturer’s guidelines.
Disconnect the hot water heater from the rest of the system so that chlorine-treated water may be routed via the hot water distribution system Using a powerful chlorine solution, backwash and clean-water softeners, sand filters, and iron removal filters may be cleaned.
It is recommended that you remove or bypass any activated-carbon filters, water softeners, and a large number of whole-house, point-of-entry, and point-of-use filters until the chlorine has been washed out of the system.
| Well casing diameter(inches) | Water volume per foot ofwater depth (gallons)* |
| 4 | 0.65 |
| 6 | 1.47 |
| 8 | 2.61 |
| 10 | 4.08 |
| 12 | 5.88 |
| 18 | 13.22 |
| 24 | 23.50 |
| 30 | 36.72 |
| 36 | 52.87 |
Capacity of water computed by multiplying the volume of a cylinder by the cubic foot rate of 7.48 gallons per cubic foot.
You may use our Wellbore Volume Calculator to get an estimate.
Calculating the Amount of Chlorinating Chemical to Put Into the Well
The business that built the well should be able to supply you with information on the depth of the well and the water level in it. Consider the following scenario: you have a well that is 100 feet deep, and the water level is 40 feet below the top of the casing. The well has a total depth of roughly 60 feet (100 – 40 = 60 feet) of water.
Step 2 | Determine the volume of water in the well.
You measured the internal diameter of the well and discovered that it was 6 inches in diameter. Using Table I, calculate the gallons per foot of depth for a 6-inch deep well. The depth of the water in the well (60 feet) would be multiplied by 1.47 gallons of water per foot of water depth (from Table I) to obtain 88.2 gallons of well water (60 x 1.47 = 88.2 gallons of water in the well).
Step 3 | Estimate the volume of water in the distribution system.
Include all of the water storage in your system, including your water heater and pressure tank. Then add 50 gallons to account for the water pipeline. In the case of a 30-gallon hot water heater and a 10-gallon pressure tank, you’ll need to install an additional 90 gallons to accommodate the distribution system.
Step 4 | Determine the water contained in the entire system.
To acquire 180 (178.2) gallons of water, multiply the volume of water in the well by the amount of water in the distribution system.
Step 5 | Determine the amount of chlorine product required for a 200 ppm solution.
Shock Well Disinfection is performed using a method and chemical that has been certified by the National Sanitation Foundation (NSF) for use in drinking water. This product contains 65 – 75 percent accessible chlorine, and only 4 ounces of this dry chemical is required to treat 100 gallons of water. This product contains 65 – 75 percent available chlorine. For the sake of this example, we would need to add 8 (7.2) ounces of this permitted chemical to the mix. Some consumers and contractors will only use laundry bleach in emergency scenarios, according to the company.
Standard bleach contains 5.25 percent chlorine that is readily accessible.
In order to meet our example, you would need at least 6 (5.4) pints of beer.
Table 2 |Amount of chemical necessary to produce a chlorine concentration of about 200 parts per million (ppm).
| Chemical Name | Amount per 100 gallons of water* |
| Liquid Laundry Bleach (5.25% NaOCl) | 3 pints |
| Commercial Strength Bleach (12-17% NaOCl) | 1 pint |
| Chlorinated Lime (25% CaOCl 2) | 11 ounces |
| Dairy Sanitizer (30% CaOCl 2) | 9 ounces |
| High-test calcium hypochlorite** (65-75% Ca(OCl) 2) | 4 ounces |
* Well water containing iron, hydrogen sulfide, or organic compounds may need the use of a higher concentration of chlorinating chemical to achieve a 200 parts per million (ppm) solution. Chlorine quickly reacts with these substances, rendering part of the chlorine ineffective as a disinfectant. * As a powder and as a pellet, concentrated hypochlorite is available for purchase (Well Safe Sanitizer Kit). The method is most effective when the pH is between 6.5 and 7.5 and the ORP (Oxidation Reduction Potential) is elevated to 650 to 700 mv, as described above.
Step 6 | Introduce the chlorine material into the well and distribution system.
A portion of the dry chlorine chemical should be dissolved in a five-gallon pail of fresh water before being introduced into the well. Make certain that the bucket is made of plastic and that it has been completely cleaned. Fill the well with the leftover dry pelletized chemical that has been stored. The pellets will eventually drop to the bottom of the well and become trapped there. Then, pour the chlorine solution into the well to complete the process. Using a hose, connect it to the water hydrant or faucet closest to the well and use it to pump water through it and back into its reservoir.
- Ensure that the interior of the well casing is thoroughly cleaned, and that no pellets or solid chlorine powder come into touch with any pitless adapters that may be present in your well during this procedure.
- Continue to recirculate the water for at least five minutes or until a strong chlorine smell can be detected.
- If any inline-filters are installed on appliances in your house, the appliances should not be utilized, and the lines to the inline-filters should be disconnected.
- Water should be allowed to flow until a strong chlorine odor may be detected at that point in the system.
- This should be done for all faucets, hydrants, and other outlets throughout the system.
A well containing iron, hydrogen sulfide, or organic compounds that are consuming chlorine might be the cause of this symptom. The absence of odor is due to an oxidizing reaction between the chlorine and something in the water, which occurs as a result of the reaction.
Step 7 | Let the chlorine disinfect the system.
To ensure that chlorine can disinfect the system, the most difficult step is to refrain from using well water for a specified period of time. It is recommended that the system be left inactive for at least 2-3 hours, preferably overnight.
Step 8 | Flush the system to remove the chlorine.
After the chlorination of the water system has been finished, the whole system must be flushed with fresh water to ensure that all chlorine has been removed from the system. If your home has a septic system or an on-site wastewater management system, you must comply with the regulations. In order to flush the chlorine from the well, we propose that you first connect to an outside faucet and direct the water to a non-grassy region or a woody landscape. It is not permissible to discharge this water into a stream, lake, pond, or wetland.
NOTE: Do not distribute waste water on gravel roads or in locations where there are no plants or aquatic life, since this might cause damage.
Step 9| Retest the water supply for bacterial contamination.
To guarantee that the water supply is clear of bacteria, a final test should be performed on the water. Take a water sample 1-2 weeks after shock chlorinating the well and analyze it according to the same protocols as previously. Despite the fact that the majority of shock chlorination treatments are effective, do not consume the water until the test findings indicate that there are no germs present in it. Every month over the next 2-3 months, test the well to ensure that contamination is not reoccurring.
The use of continuous chlorination or disinfection may be an option if bacterial contamination concerns in the water supply persist after being shock chlorinated.
It may be required to remove the water source from the equation.
It is possible that you may need to hire a professional water well contractor to do these tasks.
Remember
Water wells should be disinfected using the Well Sanitizer Pack, which we recommend using. The solution is extremely effective, is less difficult to use than liquid chlorine, and does not have any of the bad characteristics associated with ordinary household bleach. Because liquid chlorine compounds, such as home bleach, are volatile, they will decay over time if not properly stored. It is possible that household bleaches include fragrances or other compounds that might degrade the quality of potable or drinkable drinking water.
- It is not necessary to add any more cleaning agents to the chlorinated water.
- Make certain that all work spaces are properly ventilated.
- Building a new well in accordance with current building standards, as well as cement grouting in the pit and extending the casing, is the most cost-effective solution.
- Either recirculating ozonated water to the well or immediately introducing an air line carrying ozone into the well will accomplish this goal.
The usage of ozone generates unique circumstances that should only be performed by a trained specialist. When ozone is present, it can have a negative influence on some types of pipe, rubber, and other components of a private water system.
Well Disinfection – Minnesota Department of Health
Disinfection of your water system, which covers both the well with a submersible pump and the accompanying water distribution system, is explained in detail in this handout. A single family house or a commercial establishment such as a resort or campground can benefit from these guidelines. When it comes to drinking water, disinfection can help to eradicate or minimize hazardous bacteria, viruses, and other germs that may be present. You may disinfect your well yourself by following these guidelines, or you can hire a professional well contractor to do it for you.
Safety Concerns
Make sure you take these steps to protect your own safety, as well as the safety of your family, pets, and animals.
- Before beginning to disinfect your water system, make sure you have read this whole pamphlet. While sanitizing the well area, keep children and animals away from it at all times. No one should drink water from the public water supply until the disinfection processes have been completed.
Electrical
When working with electricity or water, proceed with utmost caution. Water and electricity may be lethal when used together.
Chemical
- Always follow the instructions and safety precautions provided by the manufacturer. Avoid contact with the eyes and skin. When dealing with bleach, make sure to use safety goggles or a face shield as well as rubber gloves. It is not recommended to combine bleach with other chemicals since they may produce dangerous fumes. Make sure that you don’t leave the bleach or the bleach solution alone.
Respiratory
- Disinfection has the potential to release hazardous gases. An adequate supply of fresh air must be provided around the well. When harmful gases build up in well pits, they can lead to a shortage of oxygen in the environment.
Procedure for Water System Disinfection
To disinfect your water system, you will require the following items:
- You’ll need a garden hose long enough to stretch from your water faucet to the well. Another requirement is that the hose be routed to a location where it will not interfere with your well or septic system, landscaping, or bodies of water. a 5 gallon bucket that has been cleaned
- Protective goggles/face shield and rubber gloves are required, as does a funnel. Five liters of commercially bottled water are required. Papers for chlorine testing
- Not more than six months old, an unopened bottle of non-scented household bleach with no added ingredients
| STEP 1 – Isolate critical areas | ||||||||||||||||||||||
| Turn or push the bypass valves to the “bypass” or “out ofservice” position for all water treatment devices (water softeners, reverseosmosis systems, etc.) and appliances that cannot tolerate bleach. These mayharbor organisms and need to be disinfected separately. Follow manufacturer’sinstructions for disinfection procedures.Remove all filters from devicesand appliances. Bait tanks and livestock watering troughs may require specialattention. | ||||||||||||||||||||||
| STEP 2 – Electrical safety | ||||||||||||||||||||||
| Turn OFF the electrical power to the pump. If the circuitbreaker box has a lockout hasp, use it to prevent the breaker from beingaccidentally turned ON. | ||||||||||||||||||||||
| STEP 3 – Open the well | ||||||||||||||||||||||
Open the well by:
Note:If the well is different fromthose described, contact Minnesota Department of Health (MDH) or an MDHlicensed well contractor. You will find MDH contact information on the lastpage of this document. |
Figure 1Figure 2 | |||||||||||||||||||||
| STEP 4 – Inspection | ||||||||||||||||||||||
Inspectall well components by examining:
It is important thatany plumbing or well defects are fixed so that surface water or othercontaminants cannot enter the well. |
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| STEP 5 – Mixing a bleach solution | ||||||||||||||||||||||
Water chemistry and water system sizes vary.These differences will determine the amount of bleach solution that will beneeded to properly disinfect your water system. You want between 50-200 partsper million (ppm) of bleach in the recirculating water (Step 7) fordisinfecting your water system. Do not mix bleach solution that is greater than200 ppm.
The quantity of water contained within a well is equal to the overall depth of the well minus the static waterlevel within the well. If you are unsure about the amount of water in your well, visit the Minnesota WellIndex or call the Minnesota Department of Health. The overall depth of the well should be used if it is not possible to identify the exact amount of water present in the well. The bleach solution in this table is effective for sanitizing a well as well as the water system in an ordinary home, including waterpipes, water tanks, and a water heater, among other things. If any of the following apply, you may need to increase the amount of bleach solution:
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| STEP 11 – Disinfecting water treatment systems and appliances | ||||||||||||||||||||||
| To disinfect water treatment systems and appliances, followthe manufacturer’s instructions for each water treatment device or appliance.If disinfection information is unavailable, contact your water treatment orappliance service provider. Bleach solutions may damage or improperly disinfectfilters that are a part of a water treatment system or appliance. | ||||||||||||||||||||||
| STEP 12 – Reconnect appliances, water softeners, and other treatment devices | ||||||||||||||||||||||
| Return bypass valves to ON position after following themanufacturer’s directions for disinfecting appliances and water treatment devices. | ||||||||||||||||||||||
| STEP 13 – Test the water | ||||||||||||||||||||||
| After the bleach solution is removed from the water system,it is recommended that you take a water sample to make sure that the well watertests negative for total coliform before you use it for drinking or cooking.
MDH recommends using an accredited laboratory to test your water. |
Follow-up
It is possible for total coliform to re-grow in the water system. As a result, it is critical to check your water between two and four weeks after disinfection has occurred. If complete coliform is identified, the disinfection procedure should be repeated. If total coliform has been developing in a water system for an extended length of time, it is not uncommon to disinfect the system numerous times in order to completely eradicate it. If disinfection measures are ineffective, it is possible that the well may need to be cleaned in addition to treated.
See the “WellOwner’s Handbook (PDF)” for further information about your well and water system.
Contact Information
For further details, please see: Getting in Touch with the Well Management Section. Questions? Click here to go to the top of the page. Contact the MDH Well Management Section at 651-201-4600 or [email protected] or by email at [email protected] Department of Health and Human Services of Minnesota