Unintended Consequences of Chloramine Hit Home

Abstract

The known drawbacks of chloramination include nitrification, elastomer decay, and required pre-treatment steps for fish culture and dialysis patients. To date, there has been no explicit consideration of adverse consequences of chloramination on property and water quality in buildings. Specifically, the effect of chloramine on re-growth of bacteria during stagnation, plumbing failures and lead leaching are poorly understood. Potential problems with bacterial re-growth can arise in building plumbing systems after chloramines decay and form free ammonia. Autotrophic nitrifying bacteria convert the free ammonia to nitrite and nitrate while creating organic carbon in the form of biomass and soluble microbial products. The levels of organic carbon created by nitrifiers are sufficient to support the growth of heterotrophic (HPC) bacteria. In one water tested with long stagnation times, HPC reached 106-107 cfu/ml using chloramines, whereas HPC was 1000x less when chlorine disinfectant was used. The decay of chlorine does not release nutrients for bacterial growth—a significant advantage relative to chloramine in situations with low flow and long detention times. Because the water within home plumbing is rarely sampled for bacteria, the true extent of the problem is not detected by routine distribution system