Shields Katherine F, Bain Robert E S, Cronk Ryan, Wright Jim A, Bartram Jamie
The Water Institute, University of North Carolina at Chapel Hill, Chapel Hill North Carolina, USA.
Environ Health Perspect. 2015 Dec;123(12):1222-31. doi: 10.1289/ehp.1409002. Epub 2015 May 8.
Access to safe drinking water is essential for health. Monitoring access to drinking water focuses on water supply type at the source, but there is limited evidence on whether quality differences at the source persist in water stored in the household.
We assessed the extent of fecal contamination at the source and in household stored water (HSW) and explored the relationship between contamination at each sampling point and water supply type.
We performed a bivariate random-effects meta-analysis of 45 studies, identified through a systematic review, that reported either the proportion of samples free of fecal indicator bacteria and/or individual sample bacteria counts for source and HSW, disaggregated by supply type.
Water quality deteriorated substantially between source and stored water. The mean percentage of contaminated samples (noncompliance) at the source was 46% (95% CI: 33, 60%), whereas mean noncompliance in HSW was 75% (95% CI: 64, 84%). Water supply type was significantly associated with noncompliance at the source (p < 0.001) and in HSW (p = 0.03). Source water (OR = 0.2; 95% CI: 0.1, 0.5) and HSW (OR = 0.3; 95% CI: 0.2, 0.8) from piped supplies had significantly lower odds of contamination compared with non-piped water, potentially due to residual chlorine.
Piped water is less likely to be contaminated compared with other water supply types at both the source and in HSW. A focus on upgrading water services to piped supplies may help improve safety, including for those drinking stored water.
获得安全饮用水对健康至关重要。对饮用水获取情况的监测侧重于水源处的供水类型，但关于水源处的水质差异在家庭储存水中是否依然存在的证据有限。
我们评估了水源处和家庭储存水（HSW）中粪便污染的程度，并探讨了每个采样点的污染情况与供水类型之间的关系。
我们对通过系统评价确定的45项研究进行了双变量随机效应荟萃分析，这些研究报告了按供水类型分类的水源水和家庭储存水中无粪便指示菌的样本比例和/或单个样本的细菌计数。
水源水和储存水之间的水质大幅恶化。水源处受污染样本（不符合标准）的平均百分比为46%（95%置信区间：33，60%），而家庭储存水中不符合标准的平均比例为75%（95%置信区间：64，84%）。供水类型与水源处（p < 0.001）和家庭储存水（p = 0.03）的不符合标准情况显著相关。与非管道供水相比，管道供水的水源水（比值比 = 0.2；95%置信区间：0.1，0.5）和家庭储存水（比值比 = 0.3；95%置信区间：0.2，0.8）受污染的几率显著更低，这可能归因于余氯。
与其他供水类型相比，管道供水在水源处和家庭储存水中受污染的可能性较小。将重点放在升级为管道供水的水服务上可能有助于提高安全性，包括对那些饮用储存水的人而言。
