Shocking Situation

Dec. 29, 2017
Shocking a well to remove coliform bacteria

About the author: Riley Knox is owner and operator of Knox Home Inspections LLC. Knox can be reached at [email protected] or 603.556.3155.

If you are buying a home with a well system and not public water, you should perform a water quality test. It is best to test the water during the due diligence period you have as a buyer so if anything issues appear in the test results you will have time to consider the options and work out a solution. Depending on the contaminants you need to remove, filtration systems can be expensive.

Finding Coliform

The most common water quality issue I encounter during the home inspection process is the presence of coliform bacteria. A coliform test is required for U.S. Department of Veterans Affairs mortgage loans. If coliform is present in a home purchased with this type of loan, it will need to be removed prior to the sale.

Coliform bacteria is referred to as an “indicator” organism. Not all coliform will carry diseases, but they can indicate the presence of other bacteria and viruses that can cause illnesses, such as E. coli.

If the test comes back with coliform present, you should treat the well system. This can be done by installing a whole-house chlorination system, open-air chlorination system or ultraviolet filtration system. Each home is different, and a water quality and filtration professional should be consulted before you invest in a system.

If a filtration system is out of your price range, another option is shocking the well. This process involves putting a bleach solution into the well and flushing out the system. There is a chance that the bacteria can return and you should test your water regularly if you do not have a filtration system in place.

If you are a homebuyer and your potential home has coliform present, a professional should shock the well, unless you plan on doing it yourself. The current homeowners should not shock the well on their own. They may have an inexperienced or unqualified person do it, or they may not even do it at all but tell you they did. I bring up this possibility because I have seen it before. If you are going to have the sellers correct the issue, make sure you get receipts from a professional well company and follow up with another test to ensure the bacteria is gone.

Shocking Process

Below is a basic guideline on shocking a well. Keep in mind that every system is different and may need different procedures. A typical solution for shocking a well requires 2 quarts of bleach and 10 gal of water. Follow these instructions:

  1. Dump the solution into the well. 
  2. Run a hose from the home to the well and run the water into the well to promote mixing of the solution. When you smell bleach coming out of the hose, shut it off. 
  3. Allow the well to sit for a few hours.
  4. Run the exterior hoses away from the home and any plants and vegetation.
  5. Run all interior faucets and flush the toilets.

The flushing process can take a few hours or may require repeated flushing over a few days. You may see brown water coming out of the faucets. This is common and happens when the bleach solution breaks up sediment. Keep running the water and it should work itself out.

When you no longer smell bleach at the faucets, the process is complete. Chlorine test strips can also be used.

You should retest your water about a week after shocking to ensure the bacteria is removed.

During the shocking process you should not use your water supply. In particular, avoid drinking the water, showering, giving water to pets, watering plants and doing laundry. The bleach may discolor your clothes and the rust deposits may stain them.

Other Situations

Like any issue found during a home inspection, coliform bacteria is easily fixed if handled properly. If shocked properly, the water might remain clean for a long time or it might not. Most experts will advise you to test your well water once a year, while some say every other year. If you have a shallow-dug well, you may want to test your water twice a year or more—especially if you live a quarter mile from a dairy farm with 100 cows.

I also have seen coliform form inside of a water-softener brine tank. The salt had not been filled, and the tank had filled with water, which had a thick layer of growth on top of it. A plumbing cross connection also can backflow wastewater into the system, causing contamination.

There are many ways that coliform and other bacteria can enter your water supply and several ways to treat it. A high-quality filtration system is the ideal solution, but if that is not in the budget, hopefully a bottle of bleach is.

About the Author

Riley Knox

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