Since 2014, the City has been adding phosphate to the drinking water treatment process. Phosphate forms a protective coating inside all pipes and household plumbing fixtures, which helps to reduce the potential for lead to enter tap water.
Corrosion control is mandated and approved by the Ministry of the Environment, Conservation and Parks (MECP) under the Safe Drinking Water Act.
Toronto’s Corrosion Control Plan was adopted by City Council, and is supported and endorsed by Toronto Public Health as a safe way to reduce the amount of lead in tap water and the associated health risks.
Read the latest Annual Lead Mitigation Update on the City of Toronto’s Lead in Drinking Water Mitigation Strategy.
The addition of phosphate in source water may change the type and amount of precipitate that deposits and insulates commercial heat exchangers. As a result, companies may need to decrease their number of operating cycles, or alter their chemical treatment. It is recommended that companies contact their heating and cooling supplier or process consultant to discuss whether slight modifications are needed.
The impact of phosphate on boilers should be minimal. Many customers already add phosphate to precipitate calcium and/or as a tracer in their boiler system. The addition of phosphate to the drinking water treatment process will increase phosphate levels in the boiler feed water, and ultimately, in the boiler water. For this reason, customers already adding phosphate to precipitate calcium may benefit from the implementation of Corrosion Control. These customers should measure their background phosphate levels and adjust their own phosphate dosage accordingly. Customers currently using phosphate as a tracer may need to find an alternative.
The majority of companies that additionally treat the City’s drinking water for use as a product ingredient will not require adjustments. However, it is recommended that companies contact their process consultants to confirm.
The addition of phosphate will decrease the pH of the water by less than 0.1 pH units.