Hanoi has grown rapidly into a modern,vibrant city. However, the development of infrastructure andservices has lagged behind the growth of the population. Inparticular, two significant water-related problems havearisen. Water pollution has become a major issue, creating ahuge environmental and public health hazard, impairing theliveability of the city, deterring investors, andcompromising downstream agriculture and the ecologicalintegrity of the river system. Flooding is also becoming amajor problem in many districts, occurring whenever there isa cloudburst. The city’s master plan addresses these twochallenges of pollution and flooding but implementation hasnot kept pace with the growth of the problems. To support aneffective implementation of the master Plan, the World Banksupported Hanoi City to study the problem of pollution inselected hotspots with a focus on the four main riversrunning through the city and the problem of urban floodingin two key districts. This policy note draws on the findingsand recommendations of the World Bank-financed technicalassistance to the city. This study is also in line with theWorld Bank’s ongoing collaboration with the government ofVietnam to help develop strategies and to identify thefundamental shifts needed to achieve national water security.