Toronto's Water Supply

Residents of Toronto take for granted an abundant supply of safe water from their taps. Being next to a Great Lake, it looks easy to supply water to our city; however, it is not quantity, but quality of water, that is the difficult. Early residents got their water from wells, streams, and the lake. In the early 1800s, many public wells were dug and, in 1843, a private company built a small water system to serve those able to pay. By 1856, as only 10% the houses were serviced, Toronto City Council appointed a committee to study the situation, but it was not until 1872 that it got legal authority for a public water supply.

A natural infiltration basin was constructed on Toronto Island with a one meter cast iron pipe to moved water under the bay to the John Street Pumping Station. In 1874, Rosehill reservoir was built. In the early 1890s the original intake pipe broke contaminating the waters of the bay which resulted in a typhoid epidemic. Residents demanded a better water supply. A better filtration plant and intake were constructed on the island and a brick-lined, 25 metre diameter tunnel was built under the bay to take the filtered water to the mainland. When built, the Island Filtration Plant was one of the largest in the world. The addition of chlorine to the raw lake water to destroy bacteria was tried and made an immediate impact. The death rate due to typhoid dropped from 44 to 22 deaths per 100,000 people to practically nothing. In the 1910 Toronto, there were 40.8 typhoid deaths per 100,000 inhabitants. In 1911 - 20.0; and by 1915 the rate had dropped to 1.0. It is now negligible. The R.C, Harris Filtration Plant, in the Beach, was built in the late 1930s; The R.L. Clark, in Etobicoke, in the 1960s; and the F.J. Horgan, in Scarborough, in the 1970s.

Before water reaches our taps, it is screened to remove debris, filtered, disinfected and then pumped though a distribution system. A series of pumps is used to push the water from the lake level to reservoirs and local distribution systems. Ten reservoirs and four elevated tanks provide stable water pressures and maintain the supply of water for emergencies and peak period use. Toronto’s ten ground level reservoirs are enclosed concrete structures built into the ground. The roofs of the reservoirs are landscaped for park use.

Toronto’s four filtration plants, 21 pumping stations, 10 reservoirs, four elevated tanks and miles of pipe are monitored 24 hours a day centrally at the High Level Pumping Station on Poplar Plains Road. Officers there control the operation of all pumping stations and ensure adequate water pressure throughout, using automatically provided information on pressures, flows, etc.