World facing "silent emergency" as billions struggle without clean water or basic sanitation, say WHO and UNICEF.
D003247:Conservation of Natural Resources; D003710:Demography; D014943:Global Health; D006801:Humans; D011204:Poverty Areas; D012499:Sanitation / Q000592:standards / Q000706:statistics & numerical data*; D012959:Socioeconomic Factors; D014480:United Nations; D018508:Water Purification / Q000592:standards / Q000706:statistics & numerical data*; D014881:Water Supply; D014944:World Health Organization