The WHO/UNICEF Joint Monitoring Programme (JMP) for Water Supply and Sanitation is the official United Nations mechanism tasked with monitoring progress towards the Millennium Development Goal (MDG) relating to drinking-water and sanitation.
The JMP has established a standard set of drinking-water and sanitation categories that are used for monitoring purposes. An "improved" drinking-water source is one that, by the nature of its construction and when properly used, adequately protects the source from outside contamination, particularly faecal matter. An "improved" sanitation facility is one that hygienically separates human excreta from human contact. The definitions used by the JMP are often different from those used by national governments. Estimates in JMP reports may therefore differ from national estimates.
Source: WHO/UNICEF Water Supply Statistics, 2015 Population with Unimproved Sources of Drinking Water | Population with Unimproved Sanitation Facilities