I sent an email notice on Thursday regarding a bacti sample result exceeding allowed MCL (maximum contaminant level) and on Saturday regarding chlorination of the water system. This update provides more information on the issue and our steps to resolve.
Please note that our water remains generally safe and that testing for dangerous bacteria (E. Coli or fecal coliform) returned negative (safe) results.
Issue Overview
We test our water monthly for coliform bacteria, as required by the U.S. EPA and WI DNR. Normally this returns a result of “safe” which means detected level is below the MCL set by the EPA. Our sample collected on Monday 10/5 returned a result above the MCL (unsafe) which triggers additional confirmation testing to rule out a false positive or local contamination. Multiple follow-up samples collected on Thursday 10/8 also returned levels exceeding MCL, with the exception of our “raw water” sample taken directly at the well. This indicates there is an undesirable level of bacteria in the reservoir, tank and distribution pipes, but not in our ground water source.
As a result of the confirmed results, we initiated chlorination of the water by adding a diluted solution to the reservoir and activating our chlorinator pump. The pump adds chlorine to the well water when the pump runs, injecting as it enters the reservoir. This is a similar system to what municipal water systems use to constantly chlorinate their water. The chlorine level on Saturday was higher due to our initial treatment, and was reduced to a level that should not be highly detectable.
Because of the rapid emergency chlorination, we did not issue a boil water notice. On Monday 10/12 the DNR issued an official notice of noncompliance, and recognized our disinfection response as meeting the requirements to respond to this test result. We are required to deliver a public notice to all homes within 30 days regarding the noncompliance, and board members are performing this delivery 10/13-10/15.
This chlorination process is not optional. Lacking chlorination we would be under boil water notice, and would not be able to lift that notice until multiple safe sample results. Eventually, the DNR would shut down our well if we did not treat the problem.
Our goal is to use this disinfection, and other steps such as flushing the mains, to resolve the elevated bacteria level and restore our safe level.
Next Steps
We will continue the chlorination for at least one week, to allow time for the treatment to have effect. Testing too quickly could lead to additional violations, which would incur more sampling requirements and more cost. In consultation with our certified operator and the DNR, we will take follow-up samples and after we have 2 consecutive sets of 2 safe samples, we can choose to discontinue chlorination.
During the time we are chlorinating, we will test chlorine levels at least twice weekly, at homes in different parts of the system. We are required to maintain an effective threshold in the distribution system (0.5 mg/L) and at the same time we want to avoid a nuisance level of chlorine.
After resolving this violation, we must look at the condition of the reservoir, tank and mains, and consider the best approach to maintaining our safe water status.
Questions/Answers
Q. Does this coliform violation mean our water is unsafe?
A. No. In fact the follow-up tests confirmed no E. Coli or fecal coliform, which are the dangerous bacteria. The DNR recommends you throw out ice and beverages made from the water before we disinfected, as a precaution. As explained in this DNR publication, “Coliform bacteria are naturally occurring in soil and are found on vegetation and in surface waters…. coliform bacteria do not cause illness in healthy individuals.”
The publication also notes that “their presence in well water indicates the water system is at risk to more serious forms of contamination” and “Water from a well properly located and constructed should be free of coliform bacteria” which is why we are disinfecting our system.
Q. Are we under a boil water notice?
A. No. As a result of the confirmed results, we initiated chlorination of the water by adding a diluted solution to the reservoir and activating our chlorinator pump. Because of the rapid emergency chlorination, we did not issue a boil water notice. On Monday 10/12 the DNR issued an official notice of noncompliance, and recognized our disinfection response as meeting the requirements to respond to this test result.
Q. Should we drink bottled/filtered water?
A. This is a decision for each resident on our well to make, but it is never a bad idea to at least filter your drinking water (e.g. refrigerator filter, Britta pitcher) due to the age of our pipes and presence of particles. Right now, a simple carbon filter will effectively remove virtually all chlorine, which is good for taste. For anyone with a compromised immune system, or infant or elderly residents, there is more reason to consider using purified water.
Q. Why don’t we always chlorinate the water?
A. This has never been the practice on our well and some residents have a very strong preference to avoid chlorination. It adds cost, including the chemical cost and the requirement to regularly test the level. The DNR has recommended we institute regular continuous chlorination, but it is not required (except for disinfection such as now).
Q. I live on the well and I didn’t get the email update, what happened?
A. First of all, please ensure you are subscribed to the email list by entering your info on the subscription form on this site. Please include property address (e.g. 1000 Brook Ave.) and cell phone to help us keep in contact with members. Also, check your spam/junk folder, and using a prior email alert add the “from” email to your contacts list, which will help keep any emails out of spam/junk folders.
Finally, I did receive reports of some people who are subscribed not receiving emails. I will be sending out further emails (such as the one announcing this post) and will investigate why some apparently did not receive the Thursday or Saturday email alert.