A monitoring programme of hazardous substances was implemented in Alcantarilha’s
water treatment plant (Algarve, Portugal) since 2002, in addition to the legally established
monitoring of standard physical, chemical and microbiological parameters. The objective of this
programme was to ensure the drinking water quality regarding the waterborne disease organisms
Cryptosporidium, Giardia, Salmonella, Pseudomonas aeruginosa, enterovirus and cyanobacteria,
and the potentially harmful chemicals aluminium, cyanotoxins, and disinfection by-products (THM)
and their precursors (TOC, DOC, UV254nm, SUVA). Most of these parameters are new and still not
regulated by the Portuguese and the European legislation. Data presented in this study refer to the
period of August 2002 to October 2003. Results show that, despite the seasonal variations of the
raw water quality, concentrations of the hazardous substances in the supplied drinking water were
far below the legal standards and the WHO’s and EPA guideline values, demonstrating the high
removal efficiencies of this treatment plant
