Contamination of local water supply systems in suburban Belgrade

Abstract

In suburban Belgrade, there are some 200 local water supply systems which are not connected to either the Belgrade Water Supply System or to supply systems operated by municipal utilities. The small systems in Belgrade suburbs are either operated by local municipality (local government) or even by the group of local citizens who have neither technical capability nor financial resources to do it properly. Roughly 200,000 of Belgrade's inhabitants obtain their drinking water from these water supply systems. The water quality delivered by these local water supply systems is often compromised in terms of microbiological, physical and/or chemical compliance with drinking water standards in addition to the general lack of strategy on water safety plans and risk assessment. WHO Guidelines on water quality standards as well as the recommendations on safety plans and whole risk assessment are strictly respected in the main (central) Water Supply System in Belgrade. Most frequently, elevated concentrations of ammonia, nitrites, nitrates and iron lead to lack of chemical compliance, while elevated counts of aerobic mesophilic bacteria and the presence of bacteria indicative of faecal pollution tend to be behind microbiological lack of compliance with drinking water standards. In most cases, failure to meet drinking water standards can be attributed to groundwater pollution. No sewer system exists in these areas, and wastewater from septic tanks, in practice infiltration wells, is in direct contact with groundwater. Of a total of 72 laboratory-tested drinking water samples, 51.3% failed to meet physical and/or chemical standards, and 73.6% failed to meet microbiological standards. Groundwater pollution can only be prevented if wastewater disposal system is provided for all households and all suburban residential areas which obtain their water supply from local water supply systems. Some possible mitigation measures have been indicated. In the interim period, water must be disinfected continually, and the feasibility of ozonation or UV irradiation, in addition to chlorination, should be assessed.