Contamination of drinking water in the Czech Republic by microcystins

In this report we present the first data on the concentration of microcystins in raw and treated drinking water samples collected at 8 treatment plants in the Czech Republic (40 samples in total). Sampling directly in the treatment plant pipelines revealed a relatively high incidence of dissolved microcystins, 61% of raw and 38% of treated waters contained detectable microcystins. Total microcystin concentrations ranged from 0.29 to 39.1 mug/L in raw water, and from 0.18 to 7.8 mug/L in treated water samples. Two out of five microcystin-containing samples of the treated drinking water exceeded the provisional guideline value of the World Health Organisation for microcystins (1 mug/L). Significant amounts of dissolved microcystins were also detected in the plant collecting water from the river. Here, there were no apparent water blooms but there were abundant periphyton biofilms containing significant amounts of cyanobacteria Oscillatoria spp. and Phormidium autumnale. Our results confirm the existing risk of drinking water contamination by cyanobacterial toxins for Czech treatment plants.