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Health Risks from Microbial Growth and Biofilms in Drinking Water Distribution Systems in Palestine

Khalid Swaileh, PhD1, , Rashed Al-Sa’ed, PhD2,
Rateb Hussein, MSc1 and Rasmi AbuHelu, PhD3

1Department of Biology, BirZeit University, Palestine, 2Water Studies Institute, BirZeit University, Palestine; 3Medical Laboratory Sciences Department, College of Health Professions, Al-Quds University, Jerusalem, Palestine;

Water distribution systems play a major role in determining the final quality of potable drinking water. Pathogenic and toxigenic microbiological agents in drinking water can cause diseases and death to consumers. The health risks associated with these pathogens range from viral and bacterial gastroenteric diseases to infections such as hepatitis A and giardiasis.

Drinking water samples (n=24) with a volume of 1000 ml were collected in sterile bottles from the distribution systems at different regions in Ramallah District in Palestine. Moreover, swabs from the inside of the water distribution system of the same regions were taken. Sample were filtered through 0.45µM membrane, and various tests were conducted on each sample including total coliform, fecal coliform, heterotrophic plate count, Pseudomonas auroginosa count, fecal streptococci, sulfite reducing anaerobes, residual chlorine, turbidity, ammonium and nitrate. For protozoa, microscopic examination was done for the swabs transported in saline from the biofilms within the same day of sampling.

Four samples out of 12 (33%) were containing too many to count for HPC. The remaining 8 samples were containing an average of 26 CFU/100 ml. Five samples out of 12 (42%) were found to contain total coliform. The number ranged between 0 and 80 CFU/100 ml. The average number of total coliform was 14 CFU/100 ml. Summer samples were found to have more total coliforms than winter ones. Neither winter nor summer samples were found to contain fecal coliforms. Residual chlorine ranged between 0.08-0.55 mg/L (average 0.24mg/L) and nitrate concentrations in drinking water samples ranged between 4.79-16.26 mg/L (average 9 mg/L). PCR results of the DNA extracted from a total of 25 samples of different origins (pipes water, tanks water and biofilm swabs) revealed that 23 samples were not containing the microbes (bacteria and protozoa) considered in this study.

Our results show that the drinking water quality in the distribution system of Ramallah District is of good quality and water intermittent supply should be avoided when possible, as this was associated with an increase in total coliform and turbidity.


 

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