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Access to safe drinking water is a fundamental requirement for good health and is also a human right. WHO and UNICEF’s indicator is based upon the “use of an improved source”. The authors of a recent study into water contamination postulated that this did not account for water quality measurements or monitor global access to safe drinking water. Researchers Robert Bain and Jamie Bartram from The Water Institute at University of North Carolina sought 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.
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Studies from online databases published between 1990 and August
2013 in Chinese, English, French, Portuguese, and Spanish were identified,
including PubMed and Web of Science, and grey literature. Using this data, the researchers
investigated the risk factors and settings where fecal contamination of water
sources was most common.
Studies in low and middle income countries 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.
However over a quarter of samples from improved sources
contained fecal contamination in 38% of 191 studies. Water sources in low-income
countries and rural areas were more likely to be contaminated. Thus, safety may be overestimated due to
infrequent water sampling and deterioration in quality prior to consumption, having profound
implications for public health policy.
These findings are important as WHO and UNICEF track progress towards
the Millennium Development Goals water target using the indicator “use of
an improved source”: this study shows that assuming that
“improved” water sources are safe greatly overestimates the number of
people thought to have access to water from a safe source, suggesting that a
large proportion of the world’s population still use unsafe water.
Access to an “improved source”, such as piped water and bore
holes provides a measure of sanitary protection but does not ensure water is
free of fecal contamination nor is it consistent between source types or
settings. International estimates therefore greatly overstate use of safe
drinking water and do not fully reflect disparities in access. An enhanced monitoring
strategy would combine indicators of sanitary protection with measures of water
quality.
Read more from PLOS
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