Quality changes of drinking water in the water supply network (case study from Lithuania)

Abstract

The purpose of this research was to examine water quality changes by distributing in to the water supply network. Water samples were collected from Varena town (Lithuania) drinking water distribution system fed by groundwater from well field. Parameters related to undesirable increasing of nitrites and nitrates concentrations have been measured considering these samples: pH, conductivity, concentration of total iron, manganese, ammonium, nitrates and nitrites. Results showed that groundwater from well field were extremely susceptible to favor bacterial growth in the pipelines. The occurrence of nitrites and nitrates in drinking water samples correlated positively with the lengths of old iron pipelines and negatively with the content of newly laid pipelines. The obtained results also showed that the potential nitrates increasing induced by the distribution of treated water could be reduced if: nitrates levels were below detection limits at the outlet of the water treatment plant; biological ammonium removal treatment implementation should reduce the levels of the nitrates and nitrites of the treated supplied water. Although the nitrates concentration increase in drinking water distribution systems, the issues with nitrites accumulation are rare in Lithuania. However, such processes still need to be proved in more extensive investigation, but these research results could be applied as a basic scenario.