Fungi Occurrence Assessment in Drinking Water Distribution Systems and Its Relationship with Fecal Indicator Bacteria

Introduction: As recommended by World Health Organization, consumption of the fungal contaminated water does not cause to serious infection, but may lead to healthy or aesthetic problems. The aim of this research was to assess the occurrence of fungi in water and its relationship with fecal indicator bacteria. Materials and Methods: 110 water samples were collected from different location of water distribution systems in Aliabad-e Katul City, North of Iran during April to November 2018. Enumeration of coliforms bacteria and fungi were performed by multiple tube fermentation and membrane filtration method, respectively; as described in Standard Methods. Results: Our results showed that fungi and total coliform were detected in 31 (28.4%) and 26 (23.9%) samples, respectively. Among samples of fungi positive, 22 (20.2%), 7 (6.4%), and 5 (4.6%) water samples were positive for Aspergillus sp., Rhizopus sp., and Penicillium sp., respectively. However, none faecal coliform and E. coli were observed in all examined samples, proposing the absence of faecal pollution in water. The mean and SD residual chlorine and pH were 0.55 ± 0.23 (mg/l) and 7.30 ± 0.30, respectively. The statistical analysis showed a remarkable difference between the prevalence of total coliforms and fungal species (P < 0.001). Conclusion: Presence of potential opportunistic pathogens fungi in potable water can be considered as a health risk, especially for immuno-suppressed individuals. Therefore, cleaning the processes such as biofilm removal and addition of the free chlorine concentration can be effective to decrease fungi contamination and total coliform from water distribution system.