PUB, Singapore's National Water Agency, commonly known as PUB, an acroynm for Public Utilities Board, is a statutory board under the Ministry of Sustainability and the Environment of the Government of Singapore responsible for ensuring a sustainable and efficient water supply in Singapore.

PUB regulates and oversees the country's entire water supply system, which comprises the water catchment systems, drainage systems, water works, pipeline network, water reclamation plants and sewage systems. In April 2020, PUB was also appointed Singapore's National Coastal Protection Agency.

The nation's demand for water is about 400 million imperial gallons (1.8×10^⁶ m³) a day, with homes and non-domestic sectors consumption forming 45% and 55% of the demand respectively, and expected to double by 2060. PUB is set to meet 80% of this demand through its NEWater and desalination technologies.

PUB's watershed management and treatment processes has ensured a continuous supply of clean and quality water for Singaporeans over the last four decades. The nation's clean and drinkable 'tap water' across the island exceeds the drinking water standards set by the World Health Organization. Singapore is named the top Asian city in water sustainability development in 2015, with the nation boasting the highest drinking water and sanitation standards in the region.