Adjusting the Joint Monitoring Programme's estimate of safe water access to account for microbial water quality and sanitary risk yields the conclusion that 1.8 billion people, or 28% of the global population, used unsafe water in 2010 (compared to JMP's estimate of 783 million or 11%). The research used data from the Rapid Assessment of Drinking-Water Quality, which inspected 1,600 improved water sources in each of 5 countries for presence of certain microbiological contaminants and sanitary risks (such as pipe breaks, supply discontinuities, poor drainage, and proximity to latrines). To extend these findings to an estimate of global access to safe water, the team used statistical methods to model the relationship between faecal contamination or sanitary risk and economic, governance, health, social, and environmental characteristics, thus capturing the effects of differences between countries.
- Some improved sources may provide water that is microbiologically or chemically contaminated, either at the source or by the time it is consumed. Unimproved sources are not likely to provide safe drinking water.
- The study estimates that 1 billion of the 5.8 billion people using improved water sources receive faecally-contaminated water.
- Applying a more stringent definition of safety, by adding low sanitary risk as a condition in addition to no faecal contamination, the number of people with unsafe water rises to 3 billion.
- JMP indicates that the Millennium Development Goal for safe water has already been met. Yet the two estimates in this report project, respectively, an 8-percentage point and a 20-percentage point shortfall of the goals in 2015.
- Lacking representative data, the study assumed no contamination between water point and time of use, though such contamination is known to occur. Furthermore, one round of water quality testing is unlikely to capture the true extent of contamination at a source over a longer period of time. The effect of both is for this data to be an underestimation of unsafe water use.
- The study did not account for household water treatment, but this is considered to have caused only a relatively small overestimation effect of unsafe water use.