Disinfecting your well for Coliform Bacteria


Step 1

Remove the well cap and dump 1 gallon of bleach into your well for every 50 gallons of water in the system, including the well.  3-5 gallons for the average well on PEI.  Use any bleach that has 5.25% Sodium Hypochlorite (Regular Javex, unscented).  3-5 gallons sounds like overkill, but part of this is because the bleach already lost much of its chlorine value on the store shelf.


Step 2

Hook a hose to the outside tap, turn on, and put the end of the hose down the well for at least 10 minutes before going to step 3.  Leave this hose running down the well until the end of step 4.


Step 3

Turn off the water heater and run hot water tap in the bath tub until you can smell the bleach then shut it off.  This might take up to 10 minutes.  The tub faucet runs at about 4 gallons per minute and the hot water tank may hold 40 gallons or more.


Step 4

Now go to every cold water tap in the house.  Remove the screen on the end of the tap.  Run each one separately until you can smell the bleach then shut it off.  Do not forget the dishwasher, washing machine, & toilets.  And remove the shower heads before disinfecting. 

If there is any question about whether or not you can smell the bleach.  Just keep dumping more down the well until the doubt is gone.


Step 5

Turn off the hose and remove it from the well and put the cap back on.  Leave the bleach in the system for a minimum of 12 hours.  Use a minimum amount of water during this period.  It's okay to flush the toilet a few times.


Step 6

Flushing out the bleach.  Run the outside tap(s) wide open until the smell of bleach is gone (may take up to 8 hours or more).  Once you cant smell bleach out of the hose, leave the hose running and go inside the house and turn on all taps and let them run until the smell of bleach is gone.



How to Take a Water Sample

You can pick up a sample bottle at any Access PEI location.


Step 1

Turn on all the cold water taps inside and outside the house and let them run for 5 minutes minimum.  The idea is to make sure the well pump is running and the sample is as direct from the well as possible.  Leave all the taps running until the of Step 3.


Step 2

Wash your hands with disinfectant soap.  Remaove the tap screen and soak the faucet to be sampled with rubbing alcohol.


Step 3

Turn on the faucet to be sampled and let it run for approx. 5 minutes.  Slow down the flow and fill the sample bottle.


Step 4

Do not rinse out the sample bottle and do not over fill it.

Do not set the cover down or turn it upside down.

Do not touch the inside of the cap of bottle with your fingers.


Step 5

Put on the cover and turn off the taps.  Keep the sample cool and drop it off (same day) at the nearest Access PEI location Monday through Thursday before 3:00 p.m, and Friday before noon.


Debate over Coliform Testing

There has always been a debate on whether to use Coliform as an indicator for contamination.  In parts of Europe, E-coli is used as an indicator, not Coliform.


This quote below is from one of the largest, most respected laboratories in the U.S:


"Coliform counts of less than 100 ppm per 100 ml sample are believed to be environmental bacteria thought of as regularly being housed in the well and not being added to by outside contamination."  Assuming that the well has been investigated and no source of outside contamination was present.  Johnson Screens - 2003


Furthermore, when your water test report has a background growth of 25 for example.  That means that there are 25 bacteria found that the lab cannot identify.  Other than to say that they are not disease carriers and are not harmful.