This report deals primarily with the analysis of the drinking-water and sanitation situation in the member countries of the Thematic Working Group on Water, Sanitation and Hygiene (TWG WSH), based on statistics published by the World Health Organization (WHO) and United Nations Children’s Fund (UNICEF) Joint Monitoring Programme for Water Supply and Sanitation (JMP) updated in 2015. This document also provides key information on selected health and development issues for TWG WSH member countries. The member countries covered in this report are: Brunei Darussalam, Cambodia, China, Indonesia, Japan, the Lao People’s Democratic Republic, Malaysia, Mongolia, Myanmar, the Philippines, the Republic of Korea, Singapore, Thailand and Viet Nam. Previous documents prepared by WHO for the TWG WSH include extensive analyses of the drinking-water, sanitation and hygiene sector as a whole, based on country-level information. A key finding of this report is that the TWG WSH region has succeeded in meeting the Millennium Development Goal (MDG) target for drinking-water and sanitation, which is to halve, by 2015, the proportion of the population without sustainable access to safe drinking-water and basic sanitation (UN, 2017). Individually, nine TWG WSH countries achieved the MDG sanitation target, but four countries (i.e. Cambodia, Indonesia, Mongolia and the Philippines) did not. All TWG WSH countries met the MDG drinking-water target except Mongolia, which fell short of the target by 13 percentage points. Overall, 77% of people in the TWG WSH region are using improved sanitation facilities, whereas 94% are using improved drinking-water sources (UNICEF and WHO, 2015). Despite an impressive effort made to provide drinking-water and sanitation infrastructure to the residents in this region, about one quarter of the population still lacks access to improved sanitation and 7% lacks access to improved drinking-water. Water-related diseases, including diarrhoeal diseases, are significant causes of death among children under 5 years old in the region. Almost 30 000 people in the TWG WSH region, especially children under 5, die each year due to water, sanitation and hygiene related diseases (WHO, 2014).