The Walkerton Tragedy and Why (and How) You Need to Report Chlorine Residuals

The state of Utah is tightening up on the requirements to monitor and report chlorine residuals. This article is designed to show you how to comply with this rule. Before we get started, however, I would like to take a moment of your time to tell a story. This is not a once-upon-a-time story, nor is it a simple allegory. This is a true and tragic tale that illustrates why the DEQ insists you report your chlorine residuals.

The city is Walkerton, a small town in Canada of about 5000 residents. In the year 2000, some farming run-off made its way into a well adjacent to the well used for the town’s drinking water, resulting in some E.Coli contamination of the drinking water. The water operators failed to take immediate action when the lab reports came back. To make matters worse, their chlorinators were not working properly. If the chlorination equipment was doing its job, the E.Coli problem would have stopped at the disinfection. Instead, droves of people started showing up at the doctor’s office complaining of bloody diarrhea and gastrointestinal infections. Almost half the people in town took ill, and seven of them died.

For his negligence, the water operator served a year in prison. Among the charges was failing to use adequate doses of chlorine, failing to monitor chlorine residuals daily and making false entries about residuals in daily operating records.

In a recent conversation I had with a regulator at the Department of Environmental Quality (DEQ), she told me that one of her biggest concerns is the practice of batch chlorination. Her definition of the term batch chlorination is the practice of turning on the chlorinators the day before you take the routine bacteria sample to make sure you will pass, and then turning them back off until it’s time for next month’s sample. This practice will save a lot of money on chemicals, but for obvious reasons it is not a good idea. If disinfection is part of your system plan, you really need to be running it every day and recording the chlorine residual every day.

When you submit your routine bacteria sample, there is a place on the chain of custody (COC) for you to enter the chlorine residual. If you enter it on the COC, we will report that value to the state when we transfer the results to their database. A lot of folks are not in the habit of entering their Cl residuals on the COC. The state will be taking a more hard-line stance on this going forward.

Cl residual from the monthly bacteria sample is only one data point for the month. They want data for every day in the month. You can do this on line. The following discussion will include several graphics. If it’s too small, click on the image to magnify, then click the back arrow to return to the article.

Go to Scroll down to the Quick Links section and choose Report Your Chlorine Residuals Online.

They want the chlorine residuals reported quarterly. Enter your state system number, select the quarter and hit the NEXT button.

For each month, enter the number of days you measured the chlorine residual and the average of these values. Type in your name & email address. Answer Yes and Submit.

Specific questions on these rules should be directed to the DEQ.