Singapore has four sources of water: local catchment, imported, Newater and desalinated water. Local catchment water involves collecting rainwater on a large scale. With the addition of the Punggol and Serangoon Reservoirs in 2011, Singapore now has a catchment area that spans two-thirds of the land surface. A catchment refers to the area from which rainfall flows into a reservoir, through a network of drains, canals, rivers and stormwater collection ponds.