Water from improved sources not consistently safe, study finds

May 8, 2014

Digging a well or accessing water through pipes does not necessarily mean a household in the developing world will have safer drinking water than if they used more traditional – and traditionally unprotected – water sources. In fact, fecal contamination still occurs in about 25 percent of water from improved sources.

These are the findings of a new analysis conducted by researchers at The Water Institute at UNC, based in the UNC Gillings School of Global Public Health, and published May 6 in PLOS Medicine.

Robert Bain

Robert Bain

Dr. Jamie Bartram

Dr. Jamie Bartram

Robert Bain, MEng, visiting scholar at The Water Institute at UNC, and Jamie Bartram, PhD, Don and Jennifer Holzworth Distinguished Professor of environmental sciences and engineering and director of The Water Institute, led the study.

At the turn of the millennium, the United Nations announced eight Millennium Development Goals (MDG) to be accomplished by 2015. The goals include halving extreme poverty and hunger, providing universal primary education, halting the spread of HIV/AIDS, reducing child mortality and ensuring environmental sustainability, among others.

One of the targets of the environment goal addresses water and sanitation: Halve, by 2015, the proportion of the population without sustainable access to safe drinking water and basic sanitation.

The World Health Organization (WHO) and the United Nations Children’s Fund (UNICEF) track progress toward the Millennium Development Goals’ water target using the indicator “use of an improved source.” This month, those organizations released a Joint Monitoring Programme (JMP) report stating that 748 million people still relied in 2012 on unimproved drinking water sources. That was the number used by the JMP to indicate how many people were drinking unsafe water.

The Water Institute study found that more people do not have safe drinking water than the WHO and UNICEF estimate suggests, as access to an improved source does not ensure water safety. Assuming that improved water sources are safe greatly overestimates the number of people thought to have access to a safe source of water, the authors say. They report that a large proportion of the world’s population still uses unsafe drinking water.

Bain and colleagues reviewed 319 studies that investigated 96,737 instances of fecal contamination of all types of drinking water in low- and middle-income countries.

Although the likelihood of fecal contamination should be considerably lower for “improved” sources, the authors found that more than a quarter of samples from improved sources (38 percent of 191 studies) contained fecal contamination. Protected dug wells in particular were rarely free of fecal contamination, and water sources in low-income countries and rural areas were more likely to be contaminated (both had odds ratios of 2.37).

The studies included in the current review rarely reported stored water quality or sanitary risks, and so these findings may not even reflect all of the situations in which people are drinking unsafe water, even from improved sources.

The research has profound implications for public health policy, the authors say, and they propose additional indicators of safe water, such as sanitary measures and water quality.

The study is particularly timely given the May 8 release of the JMP report [PDF] assessing progress on the MDG’s water and sanitation target.

Gillings School of Global Public Health contact: David Pesci, director of communications, (919) 962-2600 or dpesci@unc.edu.