¿Cumplir con la legislación nos garantiza consumir agua segura?

Current legislation on microbiological control of water for human consumption in our country, and in many others, does not include the search of human-pathogenic parasites or viruses. Even though water purification methods used for the removal of bacteria from water do also remove the great majority of parasitic forms, some of their resistance elements are not affected by chlorination treatments. Groundwater obtained from shallow wells in semi-rural areas may also constitute a risk since they are very susceptible to contamination.

The aim of this work was to quantify parasitic elements and viruses present in water for human consumption in the Province of Salta, in Argentina. For that, 60 L water samples were collected in six points located in the Province, including two sources of water: the distribution network and shallow wells. Samples were collected during dry and wet seasons. Ultrafiltration techniques were used to concentrate the water in pathogens. Optical microscopy using a Neubauer chamber for the quantification of parasite elements and real-time PCR for the quantitative detection of viruses were used.

We found a great variety of protozoa genera in both groundwater and in the distribution network. Only in groundwater samples we found helminths and in one of them also adenovirus. Results showed that there is little relation between the presence of bacterial indicators (established by legislation) and pathogens as parasites and viruses. Numerous water samples that are within the limits established by legislation (for which they would be considered acceptable as water for human consumption) had pathogenic parasites or viruses. This shows the urgent need to update the current legislation to include parasitic indicators that allow certifying that the water is safe for human consumption, therefore decreasing the risk of waterborne diseases.