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Education, reports, and statistics

Drinking water annual reports and quality test results

Lemieux Island Water Purification Plant

Ministry of the Environment - Drinking-Water Systems Regulation O. Reg 170/03

Note:
These documents are only available in pdf format.

Britannia Water Purification Plant

Ministry of the Environment - Drinking-Water Systems Regulation O. Reg 170/03

Note:

These documents are only available in pdf format.

Munster Hamlet Well System

Ministry of the Environment - Drinking-Water Systems Regulation O. Reg 170/03

Note:

These documents are only available in pdf format.

Shadow Ridge Well System

Ministry of the Environment - Drinking-Water Systems Regulation O. Reg 170/03

Note:

These documents are only available in pdf format.

Vars Well System

Ministry of the Environment - Drinking-Water Systems Regulation O. Reg 170/03

Note:

These documents are only available in pdf format.

Kings Park Well System (Richmond)

Ministry of the Environment - Drinking-Water Systems Regulation O. Reg 170/03

Note: These documents are only available in pdf format.

Carp Well System

Ministry of the Environment - Drinking-Water Systems Regulation O. Reg 170/03

Note: These documents are only available in pdf format.

Let’s Explore – Water Treatment (brochure)

Download a printable version of the Water Treatment Process brochure.

The City operates two water purification plants, Britannia and Lemieux Island. Both are located on the edge of the Ottawa River, one in the city's west end, the other near the downtown core.

The water from the Ottawa River is typical of a northern river, being very soft and naturally "tea" coloured; this comes from the decay of leaves and bark. It also contains algae, bacteria and viruses - all of which are removed during the six to eight hour treatment process.

The City uses a combination of physical and chemical steps to treat the water, a "multi-barrier approach." It provides the best public health protection.

Ottawa's water treatment plants:

  • Use less than one per cent of the Ottawa River's flow for the city's drinking water supply
  • Clean an average of 290 million litres of freshwater every day - enough to fill 4,000 backyard swimming pools. Together, both plants have a maximum capacity of 760 million litres per day.
  • Produce first-rate quality drinking water. Since 2009, Ottawa has received only perfect scores in the annual inspections done by Ontario's Ministry of the Environment.

The Water Purification Process

1. Intake

The water enters the plant through large pipes located on the bottom of the river. Coarse metal screens capture weeds, fish, sticks and alike.

2. Coagulation, Flocculation and Sedimentation

Chemicals are added to the water so that small particles merge to form bigger ones that look like snowflakes. These so called "floc" particles also trap most of the colour, dissolved organic matter, bacteria and viruses. The water then flows into a large basin where the floc gradually settles to the bottom. This process removes over 95 per cent of all particles.

3. Filtration

The clear water taken off of the top of the large basins then flows down through 18 filters made of sand and anthracite, a form of coal. Here, 99.99 per cent of the fine particles are removed. After filtration, the water is sparkling clear.

4. Primary Disinfection

Filtered water enters the clear well, a disinfection tank, where chlorine is added. It then flows through a maze of channels, so that the disinfectant has time to work.

5. pH Correction

The water's pH is raised to 9.2 pH. This protects watermains, household plumbing and tap fixtures from corrosion.

6. Secondary Disinfection

Chlorine and ammonia are added. These two substances react to form chloramine, a long lasting but mild disinfectant that keeps the water purified while in the distribution system.

7. Fluoridation

Fluoride is added to prevent cavities.

8. Distribution

The water is pumped to homes and businesses through more than 2,800 kilometers of watermains - roughly the distance between here and Calgary.

The water typically travels one to two days to reach the consumer, but it can range from a few hours to 10 days. There are more than 20 pumping stations and reservoirs along the way. High pressure keeps pollutants out of the pipes.

Quality Testing

The water quality is tested at the plants and at 55 locations throughout the distribution system. Over 130,000 tests are performed each year, covering 350 parameters. Annual reports are available.

Ottawa Tap Water Facts

Here are five fun tap water facts about Ottawa's drinking water:

  1. If you stretched out Ottawa's 3,000 kilometres of water mains, you could almost reach Calgary.
  2. More than 100,000 tests are performed each year to make sure your tap water is safe.
  3. You can buy 1,000 glasses of Ottawa tap water for $1.00. Always bring a reusable water bottle.
  4. More than 15 breweries use Ottawa tap water to produce local craft beer.
  5. Ottawa's tap water production has consistently achieved a rating of 100% by the Province of Ontario