A virtual tour of the treatment steps at our drinking water treatment plant.
The crown jewel of our water treatment program, our new water treatment plant is a state-of-the-art, modern facility designed for performance, safety, and environmental sustainability. We started building the water treatment plant in early 2005 and finished in late 2009. The cost to build was about $300 million.
About the plant
Located at Deacon Reservoir, the plant:
- began sending treated water to the city on the evening of December 9, 2009,
- is about the footprint of the MTS Centre,
- has a highly automated system that monitors and controls a wide variety of instruments, mechanical equipment and electrical equipment, including 40 processors, 140 pumps, 2300 valves, and 1400 instruments,
- has additional staff to handle chemical deliveries, monitor water quality, and perform regular maintenance,
- is expected to last about 75 years with normal upkeep and maintenance,
- can treat 400 million litres of water per day,
- will be able to treat the water during a prolonged power outage.
Additional background info
The water passes through the following treatment steps:
Coagulation / Flocculation
- This step increases the size of the organic matter particles, so they can be removed more easily in the next step.
- Two chemicals are added as the water flows into the plant through two large pipes:
- The water enters the flocculation basins where large mixing devices stir the water, causing the particles to collide and stick together, creating clumps of particles.
Dissolved air flotation
- This step removes the clumps of organic matter from the water.
- The water flows from the flocculation basins into dissolved air flotation tanks.
- An air saturator takes water and supersaturates it with compressed air, making it look frothy.
- A stream of supersaturated water is injected into the tanks.
- Tiny air bubbles float the clumps of organic matter to the top of the tank.
- A series of skimmers remove the floating clumps from the surface of the water.
- The clumps are pumped to an onsite processing area.
- Ozonation helps disinfect the water.
- The water flows from the dissolved air flotation tanks to the ozone chambers.
- Liquid oxygen is pumped into an ozone generator to make ozone.
- The ozone is added to the water to:
- improve the filter performance in the next treatment stage,
- destroy most of the harmful bacteria and
- improve the taste and odour of the water.
- At the end of the process, sodium bisulphite is added to the water to remove any leftover ozone.
- The water flows from the ozone chambers to the filtration gallery where it passes through biologically activated carbon filters.
- A small amount of a chemical filter aid is added to improve filter performance.
- The filters remove remaining particles from the water, including parasites.
- Good "bugs" growing on the filters also remove natural dissolved organic matter. This reduces disinfection by-products when chlorine is added.
- The filters are cleaned by pumping air and water backwards through the filters. The backwashed water is pumped to the onsite processing area.
- Water flows from the filtration gallery through to the chlorine chamber.
- Chlorine is added to meet regulations and to kill bacteria and viruses. It is one of the most efficient disinfectants of water known to science.
- Sodium hydroxide is added to raise the pH back to about the original level so that the water is suitable for drinking.
- Water flows from the chlorine chamber into an underground reservoir (clearwell).
Ultraviolet light disinfection
- After the treatment plant processes, the water is pumped from the treatment plant's clearwell through stainless steel chambers that contain ultraviolet (UV) lamps, similar to fluorescent bulbs.
- With only seconds of exposure, the UV light rays penetrate any remaining waterborne micro-organisms such as Crytosporidium and Giardia, destroying their ability to reproduce. They can no longer cause infection and illness and are now harmless.
Our water then goes through final treatment.
Processing the material removed during treatment
Two types of materials remain from the treatment stages – solids from the dissolved air flotation system and backwash water from the filters when they are cleaned. These materials are directed to a processing area on site where:
- Backwash water from the filters settles.
- The clean water is returned to the beginning of the plant for use.
- The settled-out solids and the clumps of particles from the dissolved air flotation process are pumped to open outdoor settling ponds at the Deacon site.
- The pond contents go through natural freeze-thaw cycles, which separate the liquid and solids.
- The liquid is pumped to the sewer system for treatment.
- The solids are taken to the landfill for disposal.
- is of a higher quality than the drinking water guidelines set out by Health Canada,
- is clearer and smells and tastes better all year.
The chart below outlines the changes in water quality as a result of water treatment.
|Water quality parameter||Before water treatment
Based on 2008 testing data
|With water treatment
Based on 2010, 2011 and 2012 testing data
|Turbidity (clearness)||0.24 to 4.11 nephelometric turbidity units Average: 0.54 nephelometric turbidity units||0.11 to 3.04 nephelometric turbidity units Average: 0.26 nephelometric turbidity units||Water treatment improved the turbidity level of the water coming from the water treatment plant to normally below 0.3 nephelometric turbidity units. There were occasional disturbances in the distribution system (e.g., firefighting, valve operation) that resulted in higher localized levels.|
|Total dissolved solids||66 to 114 parts per million||146 to 195 parts per million||There was an increase due to chemical addition.|
|pH||7.13 to 7.68 units||7.22 to 7.89 units||There was a slight increase in pH.|
|Alkalinity (measured as calcium carbonate)||55 to 94 parts per million||58 to 78 parts per million||There was no noticeable change.|
|Iron||0.02 to 0.09 parts per million||0.02 to 0.18 parts per million||There was no noticeable change.|
|Chlorine (free residual)||0.10 to 1.03 parts per million||0.03 to 1.21 parts per million||There was no noticeable change.|
|Sulphate||2.7 to 3.6 parts per million||35 to 56 parts per million||There was an increase due to chemical addition.|
|Sodium||1.9 to 2.5 parts per million||26.8 to 37.9 parts per million||There was an increase due to chemical addition.|
|Chloride||6.3 to 9.7 parts per million||16 to 26 parts per million||There was an increase due to chemical addition.|
|Fluoride||0.72 to 0.95 parts per million||0.68 to 0.84 parts per million||There was no change to the fluoridation program from 2008 to 2010. Effective March 2011, the target was changed from 0.85 parts per million to 0.70 parts per million.|
|Orthophosphate (measured as PO4)||1.47 to 2.12 parts per million||1.87 to 2.16 parts per million||There was no change to the lead control program (target of 2.0 parts per million).|
|Odour||35 to 150 threshold odour number units||23 to 62 threshold odour units||Water treatment improved the taste and odour of the water.|
|Colour||<5 to 6 true colour units||2 to 7.5 true colour units||There was no noticeable change.|
Data reported was collected from various locations.
If you have any questions about water quality, contact us for more information.
Due to security and safety concerns, tours of this facility are not available.
A virtual tour of our drinking water treatment plant is available.
Last updated: April 11, 2013