Heterotrophic bacteria in drinking water distribution system: a review

Abstract

The microbiological quality of drinking water in municipal water distribution systems (WDS) depends on several factors. Free residual chlorine and/or chloramines are typically used to minimize bacterial recontamination and/or regrowth in WDS. Despite such preventive measures, regrowth of heterotrophic (HPC) and opportunistic bacteria in bulk water and biofilms has yet to be controlled completely. No approach has shown complete success in eliminating biofilms or HPC bacteria from bulk water and pipe surfaces. Biofilms can provide shelter for pathogenic bacteria and protect these bacteria from disinfectants. Some HPC bacteria may be associated with aesthetic and non-life threatening diseases. Research to date has achieved important success in understanding occurrence and regrowth of bacteria in bulk water and biofilms in WDS. To achieve comprehensive understanding and to provide efficient control against bacteria regrowth, future research on bacteria regrowth dynamics and their implications is warranted. In this study, a review was performed on the literature published in this area. The findings and limitations of these papers are summarized. Occurrences of bacteria in WDS, factors affecting bacteria regrowth in bulk water and biofilms, bacteria control strategies, sources of nutrients, human health risks from bacterial exposure, modelling of bacteria regrowth and methods of bacteria sampling and detection and quantification are investigated. Advances to date are noted, and future research needs are identified. Finally, research directions are proposed to effectively control HPC and opportunistic bacteria in bulk water and biofilms in WDS.

A Keystone Methylobacterium Strain in Biofilm Formation in Drinking Water

“…The choice of the diameter of the pipe at 30.3 mm is acceptable for drinking water pipes at the extremities where the service lines start [14,54]. In those parts of drinking water distribution systems (DWDS) the control of flow conditions is very important as the disinfectant residual has been depleted and microbial activities are higher than in the mains of DWDS [55]. Also, the conditions in service lines are characterised by longer residence times, higher stagnation periods, reduced flow rates and higher temperatures compared to the mains [56].…”

Molecular analysis of long-term biofilm formation on PVC and cast iron surfaces in drinking water distribution system

“…The rough surface may concentrate organic nutrients. Hence, the biofilm regrowth on rough surface materials such as cast iron and galvanized steel was greater than that on smooth surface of PVC pipe (Chowdhury, 2012;Yu et al, 2010), and more rapid biofilm development was also observed on iron pipes than on other piping materials (Camper, 1996). Based on these results, it can be concluded that the corrosion on the cast iron may promote the biofilm formation and possibly support more diverse niches, and hence responsible for the higher bacterial diversity of the cast iron biofilm than that on the surface of PVC (Table 1).…”

Ensemble of naïve Bayesian approaches for the study of biofilm development in drinking water distribution systems

“…This is mainly explained by the roughness of the materials, since rough surfaces provide more surface to biofilm growth and protect them from water shear forces. Pipes with a rough surface have greater potential for biofilms growth [2].…”

“…Among others, aesthetic deterioration of water [7], proliferation of higher organisms [2], biocorrosion [29] and disinfectant decay [5] are universally recognized.…”