Heads up: Nitrosamines, which are really strong cancer-causing compounds from water disinfection, have popped up in treated occurrence-of-legionella-spp-in-water-main-biofilms-from-two-drinking-water-distribution-systems/”>drinking water all over North America. How much you find depends a lot on the disinfection method and the quality of the source water. N-nitrosodimethylamine (NDMA) is the most common one we see. It mostly forms when chloramine-based disinfection reacts with certain compounds already in the source water.

\n\nKrasner, S. W.; Roback, S.; (…); Bukhari, Z.\n\n2020 | AWWA Water Science\n\nResearchers measured eight N-nitrosamines at 37 water plants across the U.S. and Canada. They also looked for five tobacco-specific nitrosamines (TSNAs) in some of these water samples. NDMA mostly showed up in systems that use chloramines, with a median of 4.4 ng/L at maximum detention time. Some chlorinated systems had a little bit, but usually less than 2.0 ng/L. After ozone treatment, but before chloramines, NDMA sometimes appeared, around 2.9 ng/L at the 90th percentile. This suggests ozone itself wasn’t making the NDMA. Interestingly, chloramine plants that temporarily switched to chlorine often made less NDMA. For example, Plant 29 cut NDMA formation from 34 ng to 4 ng on average. We saw more NDMA during spring runoff, which makes sense since source water then has higher levels of ammonia and NDMA precursors. More NDMA also formed when plants used more poly (diallyldimethylammonium chloride) (polyDADMAC). N-Nitrosomorpholene wasn’t a disinfection byproduct; it was just a contaminant and didn’t increase with chloramination. TSNAs did pop up during spring runoff, and the ammonia in the source water affected the chlorine/chloramine chemistry. © 2020 American Water Works Association\n\nThe post Occurrence of nitrosamines and their precursors in North American drinking waters. appeared first on Facts About Water.\n\nSource: Water Feed