Water purification, quality and distribution

The City of Ottawa operates two water purification plants, Britannia and Lemieux Island. Together the plants produce approximately 275 million litres of drinking water each day.

Drinking water purification process

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. A “multi-barrier” approach is used, involving a series of physical and chemical treatment steps that remove undesirable substances such as colour, suspended particles, algae, bacteria, and viruses from the water in about eight hours. Here’s how Ottawa’s drinking water is produced:

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 60 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.

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

In rural areas, the City operates six groundwater well systems. These communal groundwater systems use drilled wells to supply residents in the communities of Carp, Munster Hamlet, Richmond (Kings Park), Richmond West, 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 of Ottawa’s 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.

Each year, we perform more than 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 analyzed 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 carries out extensive research studies and experiments to better understand our treatment process and to improve drinking water quality for residents. New methods of water treatment are being evaluated at the City’s Pilot Plant Research Facility, located at the Britannia Water Purification Plant. These studies are completed in collaboration with several Canadian universities and North American research agencies.

The City of Ottawa is responsible for distributing water to approximately 900,000 residential, commercial and industrial customers. We're responsible for:

• More than 3,000 kilometres of water mains
• 32 pumping stations
• 14 reservoirs
• More than 23,000 hydrants
• More than 48,000 valves

It's a big job, and we're proud of the work we do!

Placed end-to-end, the pipes used in Ottawa's water distribution system would reach from Ottawa to Calgary. This complex network of pipes, pumping stations, storage facilities, valves, fire hydrants, water service pipes and meters is one of the largest, fully integrated water systems in Canada.

Pumping stations are located throughout the distribution system to maintain water at sufficient pressure to meet all demands.

Reservoirs and elevated storage tanks are operated to meet peak water consumption demands, while a sufficient supply of water is available to meet extraordinary demands, such as fighting fire. These reservoirs and elevated tanks 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 Information Line

For up-to-date information on water-related projects and activities, call 613-580-2424, ext. 22300.

Water bill inquiries

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

Other inquiries

Call 3-1-1.

Visual: Did you know opening sequence

Visual: Kitchen tap pours out water

Voiceover: Did you know Ottawa has some of the world’s safest and highest quality drinking water?

Visual: Number 100,000 appears

Voiceover: More than 100,000 tests are performed each year to make sure your tap water is safe to drink.

Visual: Operator monitoring water samples, clock appears

Voiceover: Water is carefully monitored at each treatment stage and observed around the clock by certified water treatment operators.

Visual: Graph appears

Voiceover: And we’re constantly improving our process to give you the very best quality.

Visual: Ottawa Logo