If you drink well water at home or at camp, early spring is a good time to test that well water for bacteria. Melting snow and running water can carry surface contaminants into your well water if your well is not properly constructed and maintained. Test your water even if it seems fine, because you cannot always taste, smell or see bacteria or other contaminants.
The test result will consist of two numbers – the first for the total coli form count, and the second for E coli. Coli forms are bacteria commonly found in soil and vegetation. Their presence in your well water indicates that surface water is gaining access to your well. Water is only supposed to enter your well from the bottom after being filtered by the soil. E coli is a bacteria associated with fecal matter and is from the intestinal tract of warm blooded animals (humans, birds, other mammals). E coli in your water can be from a malfunctioning septic system or manure pile too near the well. Dog droppings on the lawn or even mouse, squirrel, or bird droppings nearby can result in E coli in your water, especially if the well’s lid is not properly sealed or if there are any other structural defects in the well.
You may receive instructions to shock the well with bleach (chlorine) if a water sample shows levels of bacteria. Keep in mind that shocking the well with chlorine is a temporary method of disinfection used to eliminate a one-time case of bacterial contamination. Shocking should not be used routinely or repeatedly. It is not a substitute for eliminating an ongoing source of contamination or a defect in your well.
Here is the link for Waterloo Region with more information on testing your well water .
http://chd.region.waterloo.on.ca/en/healthyLivingHealthProtection/Private-Wells.asp?_mid_=32545