When drilling a new well it is required by the health department to chlorinate/sanitize the well when it is finished to make sure no harmful bacteria are present, such as Coli-form and E Coli, and the well has a potable water supply. Every well drilling company will sanitize the well when it is completed. The well then needs to sit for approximately 24 hours before it can be flushed of chlorine and a sample taken for bacteria testing. It is not uncommon to have the well sanitized several times before a negative test result for bacteria comes back meaning the well has passed inspection.
When the water lab tests the sample and a positive result for coliform bacteria occurs this prompts a test for the presence of e-coli. E-Coli does not exist without the presence of Coli-form bacteria, hence the testing for e-coli when coliform bacteria is present.
Recently we had a customer that was having problems with coliform bacteria from a new well that was drilled. The well had been chlorinated after it was installed and a positive test for coliform bacteria came back after the well had been chlorinated and flushed completely. A second chlorination / sanitizing, flushing of the well was done and another positive test occurred.
The dilemma here is the positive result for coliform bacteria may not necessarily be coming from the well itself. When sanitizing a well it is imperative to sanitize the entire home plumbing system in that same 24 hour period as the well is being sanitized. It is very common to have bacteria introduced into the household plumbing system just from washing our hands and this can cross contaminate the sample and even the well supply. This is another reason why it is suggested to have your water tested every few years. After the well has been chlorinated/sanitized it needs to be flushed completely of any chlorine residual before a water sample can be drawn. Flushing the well until it is free of chlorine can take over 24 hours before a chlorine-free sample can be drawn.
When taking a water sample for testing it is imperative to sanitize the area where the water is drawn just before you take the sample. Such as a kitchen sink faucet or an outside spigot. First of all, if using any inside faucet, remove the aerator before drawing any sample. Sanitizing the sampling point can be done in several ways.
- Use a lighter to run a flame for a short time under the faucet spout. A few seconds is fine.
- Use a cotton ball with either bleach or alcohol on it to wipe the spout area thoroughly then run the faucet for several minutes before drawing the sample.
- You can also use a small bowl with bleach or alcohol in it to “dip” the faucet spout into it for a few seconds then run the faucet for several minutes to make sure any chlorine residual is gone before drawing the sample.
- It is also imperative to NOT touch any of the rim of the water sample bottle when drawing the sample. This can also cause a cross-contamination of the water sample.
Sanitizing any well should be done by a professional
There are many problems that can occur when sanitizing a well. If the well casing is an older steel casing there are certain procedures that need to be followed to prevent scale, rust, and sediment from coming off the inside wall of the well casing and potentially causing problems with the well pump. Broken well caps, a plugged or broken vent, wellheads buried in planting beds can all be issues that need to be resolved. The well itself may need to be power flushed by the drilling company to clean it first before chlorinating/sanitizing can be started. These are one of many reasons why sanitizing a well should be left to a professional that is experienced in the proper procedures.
There are several water labs in Livingston, Washtenaw, and Oakland counties that provide testing and the materials needed. Water testing is also available through your county health department. For your families health, well being and peace of mind have your water tested every few years.
Good days and good water to you!