Water Treatment Process

Curious on how water treatment works? Here are the steps we go through in the processing of our water.

Step One
Raw Water Intake and Screening
  • Large screens remove debris from the river water. This takes place in the screen building.
Step Two
Pumping Water to the Plant
  • Water is pumped from the screen building into the treatment plant.
  • Potassium permanganate and powdered activated carbon are added to the water, which help control taste and odour when there are high concentrations of organic matter in the river water. (See our Spring Run-off page for info on smelly water during the spring.)
Step Three
Clarification: A Three Step Process
  • Coagulation: Aluminum sulfate is added to the water; this causes the small particles in the water to stick together.
  • Ballasted flocculation: The water flows through clarifiers, which are large tanks with paddles that slowly mix the water. Very fine sand that is coated with a polymer solution is added to the clarifiers. The polymer solution helps the water particles and the fine sand to coagulate forming larger heavier particles. These larger particles are called floc.

  • Sedimentation: The floc settles to the bottom of the sedimentation tanks, taking with it organic material and colour. This is then removed from the water.
Step Four
  • The water flows through dual media filters, which are made of a layer of quartz sand and a layer of anthracite coal.
  • These filters help remove fine particulate matter from the water that was not removed in the clarification process.
Step Five
Chlorine Disinfection
  • Sodium hypochlorite is used to kill the harmful bacteria and viruses that may be present in the water.
Step Six
UV Disinfection
  • Ultraviolet light is used to inactivate potential disease-causing microbes, such as Giardia and Cryptosporidium. These are microbes that cannot be killed with chlorine disinfection.
Step Seven
  • Fluoride is added to the water to help prevent tooth decay.
Step Eight
Water Stabilization
  • Caustic soda is added to adjust the treated water to an optimal pH level, which helps control corrosion within the distribution system.
Step Nine
  • A small amount of ammonia is added to the water, and provides a longer-lasting disinfection.