NDMA and seven other nitrosamines in selected UK drinking water supply systems

A survey for N-nitrosodimethylamine (NDMA) and seven other nitrosamines in six UK drinking water supply systems was conducted. At the time of the study, there was no NDMA data for UK drinking waters, and the study remains one of few globally to report concentrations of the other seven nitrosamines in water supply systems. Five of the six water supply systems were selected as probable to have elevated nitrosamine concentrations because of the known source water characteristics and/or treatment practices; the sixth supply system had none of the suspected risk factors and was included as a control case. Sampling was conducted in five intervals and included samples collected from the source water, post-filter, post-disinfection and the distribution system. NDMA was measured barely above the method detection limit (0.9 ng l⁻¹) in a few isolated samples in one distribution system; however, otherwise the majority of samples contained no detectable NDMA or other nitrosamines. An exception was that N-nitrosodibutylamine (NDBA) was consistently detected in one distribution system, up to a maximum concentration of 6.4 ng l⁻¹. There were no identifiable relationships to link source water characteristics, the particular treatment processes or distribution system contact time with the observed nitrosamine concentrations.