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.
Below are links to Fact Sheets posted today on the Environmental Health at USAID website:
– Boiling: Household Water Treatment Options in Developing Countries. January 2009. CDC Safewater/USAID. (pdf, 538KB). Boiling is arguably the oldest and most commonly practiced household water treatment method, and it has been widely promoted for decades. Organizations recommend boiling both for water treatment in developing countries and to provide safe drinking water in emergency situations throughout the world.
– Filtration & Chlorination Systems: Household Water Treatment Options in Developing Countries. January 2009. CDC Safewater/USAID. (pdf, 150KB). Several household water treatment systems incorporate both a physical filtration step for particle removal and a chlorination step for disinfection. This dual approach leads to high quality treated water.
– Safe Storage of Drinking Water: Preventing Diarrheal Disease in Developing Countries. January 2009. CDC Safewater/USAID. (pdf, 254KB). Safe storage options fall into three general categories: 1) existing water storage containers in the home; 2) water storage containers used in the community and modified by an intervention program; or, 3) commercial safe storage containers purchased by the program and distributed to users.
– Simple Options to Remove Turbidity: Preventing Diarrheal Disease in Developing Countries. January 2009. CDC Safewater/USAID. (pdf, 173KB). Filtration or flocculation remove particles and reduce turbidity. These pretreatment methods may also increase the efficacy of household water treatment products by removing contaminants that interfere with disinfection and physical filtration processes.