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Water purification, quality and delivery

City-owned wells and purification plants

Every day, the City of Ottawa’s central water supply provides drinking water to approximately 865,000 residential and industrial customers. Using the Ottawa River as a source, drinking water is treated at two purification plants and subsequently distributed through a number of pumping stations, reservoirs, and elevated tanks.

The Britannia and Lemieux Island Water Purification Plants together produce approximately 275 million litres of drinking water each day. The treatment process makes use of the “multiple barrier” principle. A series of treatment steps remove undesirable substances such as colour, suspended particles, algae, bacteria, and viruses from the water. About 100,000 water quality tests are performed on drinking water samples annually, covering 350 parameters. The results demonstrate that City of Ottawa customers receive high quality drinking water that meets all federal guidelines and provincial standards.

In rural areas, the City operates five groundwater well systems. These communal groundwater systems use drilled wells to supply residents in the communities of Carp, Munster Hamlet, Richmond (Kings Park), Greely (Shadow Ridge) and Vars with drinking water. Well water is disinfected using chlorination at each treatment facility. The Vars Well System also uses greensand filtration and activated carbon to remove iron, manganese, and natural organic matter from the groundwater. Other rural residents typically get their water from private wells.

The City prepares an annual report for each municipal drinking water system, in compliance with the Safe Drinking Water Act. 

Drinking water purification 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!

Ottawa's water quality

Ottawa's water system draws water from the Ottawa River, a plentiful source of clean, very soft water. The river water is treated using the most effective processes and equipment available to remove colour, suspended particles, algae, vegetation, bacteria and viruses. Our water-purification processes are continuously monitored, ensuring that high-quality water is pumped out of the plants and maintained as it travels through the distribution system. The result is water that is sparkling clear, fresh tasting and safe to drink.

Each year, we perform approximately 100,000 water-quality tests in municipal, provincial, federal, private and university laboratories using the most up-to-date technologies and equipment. These tests cover a broad spectrum and provide information on the physical, inorganic, organic, microbiological and radiological characteristics of the water. The results are then analysed to confirm that quality is maintained as the water travels through the distribution system on its way to homes and workplaces in Ottawa.

In addition to these processes and distribution system tests, our water quality specialists are available to respond to customer inquiries and concerns. It's our job to investigate and resolve problems quickly and efficiently. Please feel free to contact us if you have any questions.

Water research

The City of Ottawa is constantly striving to improve the quality of our drinking water, and to optimize the processes we use to treat and distribute water to our customers. We are actively working on a number of process studies and experiments to optimize our existing treatment process.

We are currently evaluating new methods of water purification such as Deferred Chlorination, Ozone, Chlorine Dioxide, Carbon Dioxide, Caustic Soda, Sulphuric Acid, Biofiltration, and Alternative Coagulants, at the City's Pilot Plant Research Facility, located in the Britannia Water Purification Plant. At present, there are 22 projects being carried out in partnership with several Canadian universities and agencies such as Health Canada, and the Research Foundation of the American Water Works Association.

This research allows the City to be proactive in implementing new technologies, providing us with drinking water of the highest quality while at the same time, reducing our operating costs.​

Water delivery

The City of Ottawa, Drinking Water Services, is responsible for managing, producing and distributing water to close to 865,000 residents and businesses in Ottawa. It is one of the largest water systems in Ontario under a single authority. Just imagine how much water you'd need to fill 2.3 million bathtubs and you'll have an idea of the amount of water we produce and distribute each day!

Our two water purification plants at Lemieux Island and Britannia provide high-quality drinking water to customers in Ottawa while four smaller communal wells supply water to most residents of Carp, Richmond, Munster Hamlet, and Vars. We're also responsible for 20 pumping stations and 14 reservoirs. It's a big job, and we're proud of the work we do!

Water Supply and Distribution

Placed end-to-end, all of the pipes used in Ottawa's water distribution system would reach from Parliament Hill to Calgary. This complex network of pipes, pumping stations, storage facilities, valves, fire hydrants, water services and meters is one of the largest, fully integrated water systems in Canada. Treated water from our two purification plants delivers crystal-clear drinking water to our residential, commercial and industrial customers.

A number of pumping stations, reservoirs and elevated storage tanks are located throughout the distribution system to pump and store water at sufficient pressure to meet all demands. These stations and reservoirs are operated to meet peak water consumption demands, while a sufficient supply of water is available to meet extraordinary demands, such as fighting fire.

The reservoirs and elevated tanks also provide up to 250 million litres of storage space, allowing occasional repairs to the supply and distribution system to be carried out without major impact on our water customers.

Contact us

Water customers can contact us for information, or with concerns, 24 hours per day.

Residents, developers, agencies and other utilities can access information or receive assistance from the following resources:

Water-Information Line

For recorded up-to-date information on water-related projects and activities, call 613-560-6089.

Water Bill Inquiries

For more information on your water bill, please send an e-mail at or call our Revenue Office at 613-580-2444.

Other Inquiries

E-mail or call 3-1-1.