Is there cyanide in my drinking water?

Topics in Drinking Water
Oral Presentation

Prepared by M. Delaney, C. Blodget
Massachusetts Water Resources Authority (MWRA), 190 Tafts Ave., Winthrop, MA, Winthrop, MA, 02152, United States

Contact Information:; 617-660-7801


Is there cyanide in my drinking water? This should be an easy question to answer since cyanide has been regulated by EPA in public water supplies for 25 years. But it’s actually a tricky question to answer due to cyanide’s ephemeral nature. Cyanide comes and goes; it gets formed and it gets destroyed. The goal of the analytical chemist is to take the sample, preserve the sample, transport and store the sample, pre-treat the sample, and test the sample while maintaining an unchanging concentration of the target analyte in the sample. This is difficult for cyanide. Moreover, regulatory drinking water testing is prescriptive, so you are required to collect/preserve/test samples closely following the regulation and analytical method. In fact, there are situations where doing this will result in cyanide forming in the sample container, giving a false positive. This is particularly frustrating since all cyanide detects must be reported in the public water supply’s annual Consumer Confidence Report. All the world will see there’s cyanide in your drinking water and everyone knows that cyanide is a potent poison. Should you test for free or total cyanide? Do you have any leeway on how the samples are collected and preserved? What test method should you use? How low is your reporting limit required to be? We will carefully explore this issue in detail, including how to avoid the regulatory pitfalls.