Effect of storage tank material and maintenance on household water quality

This study investigated water quality of household water storage tanks in Tiquipaya, Bolivia. Tank age has little effect on water quality. Storage tanks cleaned three or more times per year had statistically less Escherichia coli and turbidity than tanks cleaned less frequently (p = 0.10 and p = 0.06, respectively). There was a statistically significant difference between E. coli counts in tanks cleaned three or more times per year compared with storage tanks cleaned less than once per year (p = 0.01). Polyethylene tanks had statistically higher E. coli counts than fiber cement and fiberglass tanks (p = 0.10 and p = 0.17, respectively). Water temperatures reached their highest levels (34°C) in a black polyethylene tank and temperatures of 20 and 23°C in fiberglass and fiber cement tanks, respectively. Statistically significant increases in total coliforms and E. coli associated with an increase in temperature and a loss of chlorine residual were documented as water traveled from the treatment plant, through the distribution system, and into household cisterns and storage tanks (p values ranged from 0.02 to 0.05).