Table of Contents

Do I have bacteria in my well water?

What kind of bacteria can a lab find in my water?

Total Coliform Group

Methods of testing for Total Coliform bacteria

How do I get rid of the bacteria?

Do I have bacteria in my well water?

If you are wondering if you have bacteria in your water you can send a sample of water to a local lab by following these instructions. If you are on city water your municipality is already testing for bacteria under the Total Coliform Rule (Link to maine DEP) and you most likely do not need to worry about bacteria. Private homeowners are not required to test for bacteria, but it is recommended that you test your water at least once a year (more often if you notice a change in taste, odor or clarity of your water).

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What kind of bacteria can a lab find in my water?

Total Coliform Group

Total Coliform bacteria are a group of bacteria that are easily cultured and identified in the laboratory. If you get a bacteria test on your water at a local laboratory, it is this type of bacteria that the lab will most likely be looking for. Included in this group of Total Coliform bacteria are the Fecal Coliforms; these bacteria mostly come from warm-blooded animal wastes. One specific subgroup of the Fecal Coliform group is the E. coli group of bacteria. These E. coli are primarily from human wastes and can pose a threat to human health.

If any of these bacteria are found in your drinking water it is recommended that you do not drink it. You will need to disinfect your well to kill the bacteria. If any of these bacteria are present, they indicate a possibility, but not a certainty that your water could make you sick. Contact the lab that provided your results to you, for further details and read this NHDES Fact Sheet for further information.

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How does the lab find bacteria in my water?

The lab has four EPA approved methods of testing for Total Coliform Bacteria. They are listed from the most common to the least and I left out the fourth method, because it is rarely used and I have never done this type of testing.

Methods of testing for Total Coliform bacteria

MMO-MUG - Tells you if bacteria are present or absent (P/A) in a 100mL sample.

Membrane filtration - Tells you how many Total Coliforms are present. Also gives a P/A on E. coli and sometimes reveals Non-Coliforms.

MPN - This test gives you the most probable number of bacteria in your water sample. This test is usually done on samples that are expected to be dirty. This is also the older method of testing, now replaced by the above two methods.

Before you panic, remember that this test only tells of a possibility of a problem and does not mean that you are going to get sick just because bacteria is in your well. Now that the lab has informed you that you have bacteria in you sample you need to find out the potential source of the problem and correct it.

Potential sources of bacteria in your water and solution:

• Improper sampling, you will need to resample correctly.
• Poor well design, fix well then disinfect and resample.
• Work on your plumbing, since the last disinfection, disinfect well and resample.
• New equipment: holding tanks, pumps, pipes, etc..., disinfect well and resample.
• Rare: Leaking septic system, contact local help.

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How do I kill the bacteria?

How to Disinfect Your Well - If you have bacteria in your well you may want to disinfect. Follow these instructions kill the baacteria in your well. Be persistant with those bugs, I have seen it take two or three disinfections before the bacteria are all dead.

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