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Lead Control Program
Orthophosphate Program

When did you begin the Orthophosphate Program?
We began adding orthophosphate to the water supply in June 2000 to control lead levels in Winnipeg's tap water.

Why did you select orthophosphate?
We selected orthophosphate because it is safe and economical. It is the most efficient way to reduce lead to levels below the national guideline. The program was approved by both Manitoba Health and Manitoba Conservation. It follows the Public Health Act. Several cities in the United States and Canada use orthophosphate to control lead in tap water.

How does orthophosphate reduce lead levels in the water?
Orthophosphate works by forming a protective coating inside water pipes. This coating helps reduce corrosion that can add lead to the water supply. We add orthophosphate in small amounts in the form of phosphoric acid. Phosphoric acid is a clear, odourless liquid. By weight, it is 65% oxygen, 32% phosphorus and 3% hydrogen. It is 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 that you would get in one glass of most colas.

How much orthophosphate do you add to the water?
We add orthophosphate at a rate of 2 parts per million.

Does orthophosphate change the chemistry of the water?
Yes, a little. As we add orthophosphate to the water, the pH drops about 0.1 units below normal. This means that the alkalinity is reduced by less than 2 parts per million.

Do you check to see if the Orthophosphate Program is working?
Yes. We do this with the help of some homeowners that have lead pipes serving their homes. The homeowners volunteer to take water samples from their tap once a month. We collect the samples and analyze them for lead. The national guideline for lead is no more than 0.01 parts per million. The test results in the graph below include the average amount of lead in volunteer samples along with the average amount of orthophosphate. The results show that the average amount of lead in the tap water in these homes is normally below the guideline since we have been adding orthophosphate, indicating that the program is working.

We've had between 8 and 20 homeowners volunteering to help us monitor the success of the program. We will be replacing the volunteer sampling program with a piping system designed to replicate a lead water service to a home or building.

Average five minute flush lead concentration at single family homes with lead service connections

What is the annual cost of adding orthophosphate to the water supply?
It costs about $200,000 annually to operate the Orthophosphate Program.

Are there any other benefits to adding orthophosphate to the water?
Yes. The protective coating inside the water pipes provides other benefits including:

• extended life of household plumbing
• extended life of water-using appliances, such as hot water tanks

Do you monitor the impact of the Orthophosphate Program on the environment?
Yes. Much of our water supply ends up as sewage at the three wastewater treatment plants. Here it is treated and released to the Red and Assiniboine Rivers. Since we started the Orthophosphate Program, results of wastewater tests show:

• the phosphorus levels haven't changed much at the South End and West End plants
• the phosphorus levels are about 14% higher at the North End plant
• the phosphorus levels have decreased about 8% in biosolids
• the lead levels have decreased about 37% in biosolids

For how long will you add orthophosphate to the water?
We are committed to improving the quality of drinking water and to meeting increasingly strict guidelines. We will continue to add orthophosphate to the water after the water treatment plant is operating.

Where can I get more information on Winnipeg's water?
If you would like more information on Winnipeg's water, check out the other information on our web site or contact us.