Evaluation of the quality of drinking water in regions of Greece

The present work is a comprehensive evaluation of drinking water quality from various regions of Greece. The physicochemical parameters investigated were conductivity, total dissolved solids and pH, as well as related to the treatment of drinking water such as chloride, potassium, calcium, magnesium and sodium, heavy metals (including cadmium, copper, lead, chromium and nickel), anions and cations such as fluoride, bromide, nitrates, nitrites, ammonium, sulphates and phosphates, as well as dissolved organic carbon. The parametric values set in accordance with the Directive 98/83/EC were exceeded in the cases of lead (in 2.7% of the samples analysed), chloride (2.4%) and nickel (2.1%). Ammonium, sodium, fluoride, sulphates, nitrates and conductivity were lower than the upper limits by 2% of the total number of samples analysed. The majority of problems were identified in the Cyclades islands, particularly those characterized by scarcity of water resources. The main problems related to drinking water quality are associated with the conditions of the water supply networks, the pollution of ‘parent’ water and in particular the contamination of groundwater with pollutants of both anthropogenic and natural origin, as well as the intrusion of seawater in aquifers.

Problems related to drinking water quality in the various regions of Greece seem to correlate with a series of factors. The most important deviations from good quality, reflected in excesses of the levels provided by legislation (Directive 98/83/EC), were found in waterstressed islands (Cyclades, Crete, Dodeccanese). Their water resources are scarce, the “parent” waters are frequently affected by marine water intrusion into the aquifers and the water distribution systems are old, poorly maintained and easily corroded by the high salt content of the water and their contact with the rich in marine aerosols atmosphere. Their inhabitants therefore, cover partly their needs from rainwater collected in municipal or private reservoirs and/or water produced by desalination. Some of the old generation desalination units produce poorer quality water in comparison to new reverse osmosis units providing good-quality water. The problems found in the rest of Greece are mostly related to the contamination of surface and ground waters by sewage (as evidenced by high ammonium and phosphate content) and/or agricultural run-off or percolation of waters laden with agrochemicals (e.g. nitrates, phosphates). Pollution with heavy metals may originate mainly from old or poor quality distribution networks and piping systems. It is also clear that the best quality of drinking water is found in the big cities of Athens and Thessaloniki, where the majority of the Greek population resides and where good-quality “parent” waters are used and their treatment and distribution networks are well maintained. On the contrary, in remote areas with small populations where drinking water originates mainly from local drillings, several problems related to drinking water quality emerge, while many others may remain unidentified, since drinking water quality is not effectively monitored in these areas. Under this perspective and taking into consideration that the existing national monitoring programs of drinking water quality are not sufficient and capable of covering in a reliable way the entire country, there is a need for at least periodical ad hoc controls of high quality including correct sampling, good conservation of samples and reliable analysis.