Identification and tracking of microorganisms from the biofilms of container walls used for water storage: Case of rural communities in Burkina Faso

Safe drinking water is an important necessity for humans. In rural communities of Burkina Faso, many households use local containers for storing drinking water. During water storage, some microorganisms get attached to the surface walls of the containers to form a biofilm which can deteriorate drinking water quality over time. This study aimed at evaluating the attachment of indicator microorganisms to containers walls during drinking water storage. Raw drinking water from wells and drilling were stored in three different containers: earthenware jar, polyethylene and galvanized steel for a period of 48 h. During the experiment, attached total coliform, Escherichia coli, Enterococci, Clostridium perfringens, somatic and F-specific coliphages were measured according to standard methods. Bacteria were enumerated by using conventional membrane filtration procedure and coliphages were done using double layer plaque assays. The results showed that, the adhesion of indicator microorganisms on the surface of earthenware jar, polyethylene and galvanized steel containers was detected and this adhesion was correlated to different parameters, such as temperature, pH, turbidity, concentration of organic nutrients and indigenous microorganism communities. The survival and regrowth of indicator microorganisms on the container walls was due to the quality of raw drinking water before storage. Clay-based material was subjected to more attachment of indicator microorganisms than that of plastic-based polyethylene and metal-based galvanized steel. The lowest yield of biofilm formation by indicator microorganisms was Clostridium perfringens (<1 cfu.cm-2) while the highest was total coliform (355 cfu.cm-2). However, the persistence of indicator microorganisms on container walls during drinking water storage deteriorates the water quality more. To meet national guidelines of drinking water quality, it is important to conduct simple water treatment regime such as chlorination before and during water storage in containers.