Drinking Water Purification and Treatment Virtual Tour

The City of Ottawa operates two water purification plants, Britannia and Lemieux Island, that service roughly 90% of Ottawa households. Water from the Ottawa River is very soft and has a natural "tea" colour due to the highly forested watershed and the breakdown of leaves, bark, and trees. Microorganisms such as algae, bacteria, and viruses are removed as water passes through the treatment plants. A “multi-barrier” treatment process is used and involves a combination of physical and chemical steps to produce safe drinking water in about eight hours. Here’s how Ottawa’s drinking water is produced:

Water Purification and Treatment Process

1. Intake

  • Ottawa River water enters the treatment plant through a large intake pipe with a screen that removes objects such as weeds or fish.

2. Coagulation & Flocculation

  • Small impurities such as organic matter, algae, and bacteria are captured.

3. Sedimentation

  • Heavy particles sink to the bottom of the settling tank and clear water is collected from the top.  Approximately 95% of the impurities are removed at this stage.

4. Filtration

  • Water then flows through several filters removing 99.99% of fine particles.

5. Primary Disinfection      

  • Chlorine is added to get rid of any remaining microorganisms. 

6. pH Correction

  • The water’s pH is adjusted to protect water pipes and household plumbing from corrosion.

7. Secondary Disinfection

  • Chloramine (a mild disinfectant) is added to keep the water safe as it travels throughout the distribution network.

8. Fluoridation

  • Fluoride is added to prevent dental cavities.

9. Testing

  • More than 100,000 tests are performed each year to make sure your tap water is safe. Water quality is tested at each treatment stage and at more than 50 locations across the city.

10. Distribution

  • Clean water is pumped through more than 3,000 km of water mains – roughly the distance between Ottawa and Calgary. Approximately 250 million litres of water is stored each day in reservoirs. There are more than 20 pumping stations to maintain high pressure which keeps pollutants out of the pipes.

Enjoy Ottawa tap water – rated as one of the world’s safest and highest quality!

Interested in finding out more?

Invite the Environmental Services outreach team to provide a presentation about Ottawa’s tap water to your school or community group! All presentations are subject to audience size and outreach team availability.