Lead, a common natural metal found throughout the environment, can be harmful if too much of it enters the body. People can be exposed to lead from many sources, such as lead paint, dust, food, and air pollution. Drinking water can also be a source of lead. The Guidelines for Canadian Drinking Water Quality set acceptable levels of lead in drinking water to protect against the risk of adverse health effects.

Pearson says, "The most recent results show that, based on a five minute flushed sample, the majority of the homes in our testing program now meet the Canadian guidelines. Only a few residences are slightly above the guideline. We will continue to monitor lead levels and expect that they will continue to decrease over the next several months."

Dr. Margaret Fast, Medical Officer of Health with the Winnipeg Regional Health Authority, says, "While the health risk of exposure to lead in Winnipeg's drinking water was already low, we are satisfied that the water utility's Lead Control Program is reducing the lead levels as much as possible."

There is no detectable lead in Shoal Lake, the source of Winnipeg's water supply. However, our water is soft, and all soft water is naturally corrosive. Lead enters drinking water mainly as a result of the corrosion, or gradual wearing away, of materials in the water distribution system that contain lead, such as service pipes, plumbing fixtures and lead based solder. Tap water in most Winnipeg homes has a very low level of lead. However, tests of tap water in some homes with lead water pipes showed lead levels above the National Guideline.

Studies conducted by the Water and Waste Department confirmed that orthophosphate could be used effectively to reduce lead in Winnipeg tap water. Orthophosphate, added in small amounts in the form of food-grade phosphoric acid, works by forming a protective coating inside water pipes. This coating helps reduce corrosion that can contribute lead to the water supply. Phosphoric acid is approved for use in drinking water supplies and is also found in many popular food products, such as soft drinks. "You would need to drink more than 100 glasses of tap water to get the same amount of phosphoric acid as you would in a glass of cola," says Pearson.

On June 5, 2000, the Water and Waste Department began adding orthophosphate to the water supply to reduce lead levels in our drinking water. The amount of orthophosphate added to the water supply was gradually increased to a maximum level of 3 parts per million to establish an effective protective coating. Department staff closely monitored water quality and adjusted the quantity of orthophosphate as necessary to avoid noticeable changes in water quality.

Pearson says, "Now that the protective coating is in place, we are gradually reducing the amount of orthophosphate added to the water until a maintenance level of about 1 part per million is reached by mid May." The maintenance level will be fed to the water supply for the foreseeable future to control lead levels at customers' taps. This is the equivalent of less than 1/10 of a drop of orthophosphate in a four-litre jug.

A brochure describing the lead control program was delivered by mail to Winnipeg residents and businesses in April 2000. Customers with questions about water quality or wanting more detailed information on the addition of orthophosphate to control lead levels can call the Water and Waste Department, Customer Service Centre at 311, or visit the City of Winnipeg Web site at: