[Water quality and microbiological status of the distribution system: traditional parameters and emerging parameters]

Most pollution of drinking water is caused by inadequacy of the uptake and distribution systems, by insufficient upkeep of the sewage system and by defects or breaks in the disinfection processes. This may be the cause of waterborne epidemic outbreaks and therefore it is necessary carry out routine controls by simple and rapid tests for the detection of intestinal organisms. In the light of minor hepatitis A epidemics occurred in the town of Messina, we have carried out a study to determine the drinking water quality. To this end, in addition to the traditional tests recommended by CEE and required by the 8/2/1985 DPCM (37 degrees C and 20 degrees C viable count, total and faecal coliforms and faecal streptococci), we have carried out P. aeruginosa, coliphages and gram-negative endotoxins tests, in 74 water samples drawn on way in and way out of the tanks and along the piping system. Only 12.5% of the sixteen water samples drawn on way in (before disinfection system) was in compliance with the law. 75% of these samples showed positivity for faecal streptococci. The water quality was lower in the fourteen water samples drawn on way out of the tanks (7.1% was in compliance with the law). The percent of positivity along the piping system for total and faecal coliforms and for faecal streptococci was 34.1, 15.9 and 59.1 respectively. Coliphages were always absent. P. aeruginosa was almost always present in way in water (93.7%). Moreover this microorganism was recovered in 85.7% of the samples drawn on the way out and in 77.3% along the piping system. In the same drawing places endotoxins were present at high percentage (100%, 85.7% and 90.9%). These values come from high test sensitivity and poor water quality. Finally we have pointed out the importance of all the parameters examined. The significance of coliform bacteria is known, but we consider very important, as organisms indicative of pollution, the enterococci, since they P. aeruginosa may survive long time in fresh water though it is not autoctone, but, in general, of faecal origin. Several soluble antigens of this microorganism as well as enterococci show positive LAL tests (1-5-6). The endotoxin content in fresh water reflects the degree of bacterial contamination. We believe, therefore, it is needed to fix an upper limit to endotoxins in drinking water. Coliphages concentrations could be correlated with enteric virus concentrations but the ratio of coliforms to coliphages is about 100:1. Therefore this indicator of viral pollution is helpful only for highly polluted surface waters.