London School of Hygiene and Tropical Medicine, Keppel St., London WC1E 7H, United Kingdom.
Environ Sci Technol. 2011 Jul 15;45(14):6095-101. doi: 10.1021/es2004045. Epub 2011 Jun 23.
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 six-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/100 mL, 95% CI, 5.4-9.7) were actually worse in microbiological quality than source water (geometric mean 4.0 TTC/100 mL, 95% CI, 3.1-5.1) (p < 0.001), although both are relatively low levels of contamination. Only 60% of drinking water samples were reported to have actually been boiled at the time of collection from the home, suggesting over-reporting and inconsistent compliance. However, these samples were of no higher microbiological 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.
煮沸是家庭中最常见的水消毒方法，也是衡量其他即时用水处理方法的基准。在赞比亚城乡结合部进行的一项为期六周的研究中，我们评估了 49 户没有自来水且报告“总是”或“几乎总是”在饮用前对水进行煮沸的家庭中煮沸的微生物效果和潜在成本。每周对水源和家庭饮用水样本进行耐热大肠菌群（TTC）检测，以指示粪便污染。通过调查和结构观察收集人口统计学、成本和其他信息。从家庭采集的饮用水样本（几何平均值为 7.2 TTC/100mL，95%置信区间为 5.4-9.7）的微生物质量实际上比水源水（几何平均值为 4.0 TTC/100mL，95%置信区间为 3.1-5.1）更差（p<0.001），尽管两者的污染程度都相对较低。只有 60%的家庭采集的饮用水样本据称在采集时实际煮沸过，这表明存在过度报告和不一致的合规情况。然而，这些样本的微生物质量并没有更高。有证据表明，由于缺乏残留保护以及不安全的储存和处理，煮沸后水质恶化。煮沸所需燃料或电力的潜在成本分别估计为收入的 5%和 7%。在这种水源处水质相对较好的环境下，采取安全储存措施最大限度地减少再污染可能更有效地降低饮用水引发疾病的风险，成本仅为煮沸的一小部分。
