EFFECTS OF NITRATE REMOVAL ON
WATER QUALITY IN DISTRIBUTION FINAL REPORT Contract PECD 7/7/218
Report No DWI0001
Concern over increasing nitrate concentrations in drinking water and the need for compliance with the EC Drinking Water Directive has necessitated investigation into methods of denitrification for potable water supply. Although a number of denitrification plants exist in Europe, there has as yet been relatively little operating experience and it is considered in the UK that the effects of adopting denitrification have not been fully quantified. Of particular concern is the possibility that, by altering the chemical and microbiological characteristics of the water, the treatment methods employed may have undesirable effects on the distribution system and, as a result, on the quality of water in supply. Effects such as mains corrosion; dissolution or disturbance of previous deposits in mains; organoleptic effects due to bacterial regrowth; and increased risks of leaching of toxic metals, may have an indirect but significant effect on the long term costs of denitrification.
In the light of this, the Department of the Environment commissioned Consultants in Environmental Sciences Ltd to undertake a study of the effects of denitrification on water quality in supply, and of the potential increase in treatment costs associated with any side-effects over and above the costs of the treatment process itself. The study comprised five elements: