Shocking Your Well: The New Brunswick Way

Shock chlorination is a process used to disinfect well water systems, including wells, springs, and cisterns, using chlorine or household liquid bleach. It is a relatively inexpensive and straightforward procedure that is highly effective at eliminating harmful bacteria such as E. coli. The process involves adding a large amount of chlorine to the water in the well and pumping it through the water distribution system. This is particularly important for private well owners, who are responsible for maintaining their wells and ensuring the water is safe to drink.

Why shock chlorinate a well?

Shock chlorination is a standard treatment for sanitizing your well system. It is a relatively inexpensive and straightforward procedure used to control bacteria in wells. It is the most effective way to eliminate harmful bacteria, such as E. coli, in wells.

Wells should be shock chlorinated when a well water sample result shows the presence of bacteria. Any time a well is opened for repair, it must be disinfected. Newly-built wells should also be shock chlorinated following construction. Other reasons to shock chlorinate a well include:

• If the well has been unused for a while and is being returned to service
• If the well system is opened for any installation, repair, or maintenance
• If the well is surrounded by floodwaters (standing water around or covering the well casing)
• If well water becomes muddy or cloudy after rain
• If the well has iron bacteria or sulfur-reducing bacteria symptoms like slime (biofilm) or odor

It is important to note that shock chlorination is not a recommended method for treating recurring bacteria problems. If bacterial contamination persists, the source of contamination should be identified and eliminated by a licensed well driller or contractor. Alternatively, a continuous disinfection treatment system can be installed.

When to shock chlorinate a well

Shock chlorination is a relatively inexpensive and straightforward procedure used to control bacteria in wells. It involves adding a large amount of chlorine to the water in the well and pumping it through the water distribution system. The chlorinated water is left in the system long enough to ensure complete disinfection.

Wells should be shock chlorinated when a well water sample result shows the presence of bacteria in the water. Any time a well is opened for repair, it must be disinfected. Newly-built wells should also be shock chlorinated following construction.

Other reasons to shock chlorinate a well include:

• When lab results indicate the presence of bacteria.
• Upon completion of a new well or after pump replacement or repair.
• When the distribution system is opened for repairs or maintenance or when the system has not been used regularly.
• Following contamination by flood water, a contamination incident, or damage to the system.
• To control iron, slime, and sulfate-reducing bacteria and other nuisance issues, including discolored water, high iron, manganese, turbidity, black water, or even odors.

How to Shock Chlorinate a Well

• Turn off or close all water faucets outside and inside the house to maintain pressure.
• Tilt the top of your tank and remove some water using a bucket or can.
• Fill up your tank with water from a hose or bucket, ensuring the hose is set to "jet." Leave some room in the tank for air bubbles.
• Open the top tank valve and let the water run down the outside of the well.
• Close the tank valve and switch on the air pump.
• Open the ground valve on your well, ensuring you are not standing in water. The water pressure should be above 30 pounds. If it is less, shock the well again or call a professional.
• Close the ground valve.
• Turn off the pump and close all faucets.
• Open one faucet to release air pressure and then turn it off.
• Turn on all outside water faucets and let the water run until good pressure returns.
• Repeat step 2 every two months for best results.

Tips for Shocking a Well:

• Do not use an electric pump to shock a well as it can be dangerous.
• If the water in your well is not bubbling, the ground pressure may be low or your water heater may not be functioning properly.
• When choosing a well pump, avoid those directly connected to an electrical generator, as they may emit toxic fumes.
• If your well has electricity, ensure the fuses on your electrical panel are not blown, and the circuit breaker is not tripped or turned off.

How to shock chlorinate a well

Shock chlorination is a standard treatment for sanitising a well system and removing bacterial contamination. Here is a step-by-step guide on how to shock chlorinate a well:

Prepare

Before beginning the shock chlorination process, it is important to take some safety precautions. Ensure you have protective clothing, including goggles, rubber gloves, and boots. It is also recommended to have a bucket of fresh water ready in case any chlorine comes into contact with your skin or eyes.

Clean

Remove any debris from the well house, spring house, or storage tank. Turn off the pump circuit breaker and remove the well cap or cover. Scrub the interior surfaces with a strong chlorine solution (a mixture of half a gallon of chlorine bleach and five gallons of clean water). If the well does not have a sanitary cap, it should be replaced with a new one to prevent recontamination.

Calculate and Pour

Determine the amount of chlorine bleach needed based on the well's diameter and depth. As a general rule, use three pints of bleach for every 100 gallons of water in the well, plus an additional three pints to treat the household plumbing. Pour the calculated amount of bleach into the well.

Mix

Connect a clean garden hose to a nearby faucet and place the end of the hose inside the well. Turn on the faucet and let the water run until you can smell chlorine coming out of the hose. Use the hose to wash down the interior of the well for about 15 minutes, then close the faucet.

Circulate

Allow the chlorine solution to circulate throughout the system. Open each faucet, starting with outdoor ones, then indoor ones, and let the water run. Be sure to run hot water to draw chlorine into the water heater. Close each faucet after detecting a strong chlorine odour. Flush the toilets. If a strong chlorine smell is not present at all outlets, add more bleach to the well and try again.

Flush and Finish

Turn off the pump circuit breaker, replace the well cap or cover, and allow the chlorinated water to remain in the system for at least eight hours, preferably 12 to 24 hours. Turn on the pump circuit breaker and rid the system of the remaining chlorine by running outdoor and indoor faucets until the chlorine smell is gone. Minimise the amount of chlorinated water flowing into the septic tank.

Test

After flushing the system, sample the water and have it tested for biological contamination. If the water shows no bacterial contamination, it is recommended to still test your water annually. If bacterial contamination persists or reappears, try to locate and remove the source of bacteria, such as a nearby septic system or livestock pen.

What type of chlorine bleach to use

To shock a well, you'll need to use plain, unscented liquid chlorine bleach with a concentration of around 5-6%. Do not use bleach with any additives or scents; the label should state that the product contains sodium hypochlorite.

The bleach should be liquid laundry bleach, such as Chlorox or Purex, or a generic supermarket brand. The bleach will be diluted before use, with a maximum of 2 cups of bleach per 2 gallons of water. Straight chlorine can corrode metal well parts.

The amount of bleach you will need depends on the size of your well. You will need to determine the depth of the water in your well, which is the distance from the bottom of the well to the water level. This can be calculated by measuring the distance from the ground level to the water level and subtracting that from the well depth.

For a dug well with a 1-meter (3-foot) diameter, add 1 litre (1 quart) of bleach for every 1.5 meters (5 feet) of depth. For a drilled well with a 15-centimeter (6-inch) casing, add 142 milliliters (5 ounces) of bleach for every 7.5 meters (25 feet) of depth. For a well point with a 5-centimeter (2-inch) diameter, add 85 milliliters (3 ounces) of bleach for every 3 meters (10 feet) of depth.

How often to shock chlorinate a well

Shock chlorination is a relatively inexpensive and straightforward procedure used to control bacteria in wells. It is the most effective way to eliminate harmful bacteria, such as E. coli, in wells.

Wells should be shock chlorinated when a well water sample result shows the presence of bacteria in the water. Other reasons to shock chlorinate include when a well is opened for repair, after construction, or when flood water has entered the well. The United States Environmental Protection Agency recommends that private water supplies be tested annually for coliform bacteria to detect contamination problems early.

There is no fixed schedule for how often to shock chlorinate a well, as it depends on the presence of bacteria in the water. However, it is recommended to test the water supply annually and shock chlorinate when necessary.

• Turn off all water faucets outside and inside the house to maintain pressure.
• Tilt the top of the tank and remove some water using a bucket.
• Fill the tank with water from a hose or bucket, ensuring the hose is set to "jet." Leave some room in the tank for air bubbles.
• Open the top tank valve and let the water run down the outside of the well.
• Close the tank valve and switch on the air pump.
• Open the ground valve, ensuring you are not standing in water. Ensure the water pressure is above 30 pounds.
• Close the ground valve when air bubbles appear, indicating fresh, oxygen-rich water.
• Turn off the pump and close all faucets.
• Open one faucet to release air pressure and then turn it off.
• Turn on all outside water faucets and let the water run until good pressure returns.
• Repeat step 2 every two months or whenever the water has an odd taste or smell, or bubbles slowly.

It is important to note that shock chlorination does not correct the source of bacterial contamination. If bacteria are entering the well from a septic tank or other source, they will return even after sanitizing the well. Therefore, it is crucial to identify and address the source of contamination to prevent reoccurrence.

Frequently asked questions