Fecal contamination of drinking-water in low- and middle-income countries: a systematic review and meta-analysis

Background: Access to safe drinking-water is a fundamental requirement for good health and is also a human right. Global access to safe drinking-water is monitored by WHO and UNICEF using as an indicator ‘‘use of an improved source,’ ’ which does not account for water quality measurements. Our objectives were to determine whether water from ‘‘improved’’ sources is less likely to contain fecal contamination than ‘‘unimproved’ ’ sources and to assess the extent to which contamination varies by source type and setting. Methods and Findings: Studies in Chinese, English, French, Portuguese, and Spanish were identified from online databases, including PubMed and Web of Science, and grey literature. Studies in low- and middle-income countries published between 1990 and August 2013 that assessed drinking-water for the presence of Escherichia coli or thermotolerant coliforms (TTC) were included provided they associated results with a particular source type. In total 319 studies were included, reporting on 96,737 water samples. The odds of contamination within a given study were considerably lower for ‘‘improved’ ’ sources than ‘‘unimproved’ ’ sources (odds ratio [OR] = 0.15 [0.10–0.21], I2 = 80.3 % [72.9–85.6]). However over a quarter of samples from improved sources contained fecal contamination in 38 % of 191 studies. Water sources in low-income countries (OR = 2.37 [1.52–3.71]; p,0.001) and rural areas (OR = 2.37 [1.47–3.81] p,0.001) were more likely to be contaminated. Studies rarely reported stored water quality or sanitary risks and few achieved robust random selection. Safety may b