Water treatment: past and present
Historically, quality rather than quantity of water has been the challenge for Toronto. Early residents of the Town of York and other surrounding towns drew their water from private wells, from the various rivers that emptied into the lake, as well as directly from the lake itself. In the early 1800s, many different public wells were dug in the area to make water even more accessible.
In 1843, a new private corporation, the Toronto Gas, Light and Water Company, began to distribute water through a small scale distribution system made out of wooden pipes to citizens who could afford the cost of the service. Over the next two decades, the availability of drinking water did not get much better. In 1858, only 900 out of 9,500 houses were being serviced. In 1856, a special committee of Toronto City Council was appointed to investigate the possible takeover of the Toronto Water Works Company, but it was not until 1872, after 16 years of debate, that City Council obtained passage of an act to form a publicly administered water works service.
"Drinkable sewage"
Improvements to the system proceeded quickly after that. They included construction of a natural infiltration basin on Toronto Island to draw in lake water, a cast iron pipe one meter in diameter leading under the bay to the shore, the original John Street Pumping Station (now located just south of the Rogers Centre) and a 150 million-litre open storage reservoir (Rosehill). Problems with cloudy and disease-laden water (referred to by residents as "drinkable sewage") required the replacement of the basin with a wooden stave pipe two meters in diameter extending approximately a kilometre into Lake Ontario.
In the early 1890s this intake pipe broke and floated to the surface. The contamination of the water supply by polluted harbour water resulted in a typhoid epidemic and renewed demands from residents to draw the city's water supply from anywhere but the harbour. After much debate, American and British consultants decided to construct a slow sand filtration plant on the island to remove impurities from the lake water and to replace the broken wooden intake pipe with a steel pipe. A brick-lined, 2.5-m diameter tunnel was constructed under the bay to transport the filtered water to the mainland. The tunnel was completed in 1908, and the Island Filtration Plant, one of the largest facilities of its kind in the world at the time, was finished in 1912.
While the treatment plant was being constructed, yet another typhoid epidemic devastated the city, apparently due to contamination of the water while the main intake pipe was being repaired. A new approach to the ongoing problem was tried: chlorination. The addition of chlorine to the raw lake water to destroy bacteria made an immediate impact. The death rate due to typhoid went from 44 to 22 deaths per 100,000 people within one year, was cut in half again after the completion of the filtration plant, and continued to decline rapidly after that.
First city to use chlorine
Toronto became one of the first cities in North America to use chlorine to treat its water and continues to be a leader in this field today. Toronto was the first city in Canada to use the processes of super-chlorination (adding very high doses of chlorine), de-chlorination (adding a chemical to remove the excess chlorine), and pre-chlorination (adding chlorine to the water before filtration).
Other treatment plants were built in the Township of Scarborough (1921), the Town of New Toronto (1924) – now the Etobicoke community, and the Township of North York. Toronto and the surrounding towns continued to expand and upgrade their facilities independently, creating duplication and a lack of coordination of the systems. With the creation of the Metropolitan Toronto level of government in 1953, the responsibility for the treatment, storage, pumping and large trunk transmission of the area's water was assumed by the Metro Toronto Works Department. Usage of well water plants was discontinued and the only source of water for the system became Lake Ontario.
With the amalgamation of the seven former municipalities (East York, Etobicoke, North York, Scarborough, Toronto, York and Metropolitan Toronto) on January 1, 1998, the various Works Departments have combined to form Works and Emergency Services, which was disbanded in 2005.
Currently, Toronto Water operates four water filtration plants, three spread out along the lakeshore and one on Centre Island.