Microbiological performance and potential cost of boiling drinking water in urban Zambia.
Environ Sci Technol. 2011 Jun 8.
Assessing the microbiological performance and potential cost of boiling drinking water in urban Zambia.
Psutka R, Peletz R, Michelo S, Kelly P, Clasen T.
Boiling is the most common method of disinfecting water in the home and the benchmark against which other point-of-use water treatment is measured. In a five-week study in peri-urban Zambia, we assessed the microbiological effectiveness and potential cost of boiling among 49 households without a water connection who reported “always” or “almost always” boiling their water before drinking it.
Source and household drinking water samples were compared weekly for thermotolerant coliforms (TTC), an indicator of fecal contamination. Demographics, costs and other information were collected through surveys and structured observations. Drinking water samples taken at the household (geometric mean 7.2 TTC/100ml, 95%CI 5.4-9.7) were actually worse in microbiological quality than source water (geometric mean 4.0 TTC/100ml, 95%CI 3.1-5.1) (p
Only 60% of drinking water samples were reported to have actually been boilded at the time of collection from the home, suggesting over-reporting and inconsistent compliance. However, these samples were of no higher microbiologial quality. Evidence suggests that water quality deteriorated after boiling due to lack of residual protection and unsafe storage and handling.
The potential cost of fuel or electricity for boiling was estimated at 5% and 7% of income, respectively. In this setting where microbiological water quality was relatively good at the source, safe-storage practices that minimize recontamination may be more effective in managing the risk of disease from drinking water at a fraction of the cost of boiling.