Toronto Water is the municipal division of the City of Toronto under Infrastructure and Development Services responsible for the water supply network, and stormwater and wastewater management in Toronto, Ontario, Canada, as well as parts of Peel and York Regions.

Water treatment was originally established in order to provide safe drinking water. In the 19th century, the water off the city's shores was severely polluted by the dumping of waste from residences and businesses.

Before 1842, Toronto's water supply was manually pumped from Lake Ontario, streams and wells. Water carters would take the water and distribute it to customers across the city.

From 1843 to 1873, water was privately provided by Furniss Works or Toronto Water Works, a subsidiary of Toronto Gas Light and Water Company, which was owned by Montreal businessman Albert Furniss.

Following Furniss's death in 1872, the City of Toronto bought out Furniss Works and transformed the water supply to public hands under the Toronto Water Works Commission.

Outside of the pre-amalgamation City of Toronto each of the former municipalities had its own treatment plants and pumping stations. North York had three, one at Oriole, which was built in the 1923, the ruins of pumping station found near Duncan Mills Rd and Don Mills Rd, Steeles built in the 1930s, and Sheppard West built in the 1940s. Scarborough had one built in 1921 and New Toronto had one built in 1924. Prior to the 1950s, the municipalities were responsible for water treatment and water came from local water sources like wells and streams.

The current system was introduced in the mid-1950s, with the formation of Metro Toronto in 1954, and was managed by Metro Toronto. Since 1975, Toronto has supplied water to York Region (mostly to residents in the south end of York).

Following amalgamation in 1998, Toronto Water was created from the Toronto Works and Emergency Services and once part of Metro Toronto Works department.