Calgary wastewater data: treatment results, flows and virus monitoring, and how to read them

01 /What wastewater data does Calgary publish?

Calgary's wastewater data fall into three families: what leaves the treatment plants, what the wastewater says about community health, and what the pipe network is made of. Each answers a different question and has different limits.

02 /What do the treatment plant effluent data show?

They show how much treated water each plant releases to the river and what is left in it. The City describes the dataset as results that are reported monthly to Alberta Environment and Protected Areas, covering laboratory and flow data for the plants' treated effluent from 2007. Laboratory results come from daily 24-hour composite samples, except fecal coliforms, which come from grab samples, and the City's laboratory is accredited to the ISO/IEC 17025 standard.

The parameters include ammonia as nitrogen, biochemical oxygen demand, fecal coliforms, effluent temperature, mercury, nitrite plus nitrate, total Kjeldahl nitrogen, total phosphorus, total suspended solids and total effluent flow to the river. Sampling sites are listed per plant, with separate after-UV sites for disinfection results.

The river downstream has its own record too: the City's watershed sampling data, used in sewage leaks and the Bow River, show how bacteria levels change as the Bow crosses the city. Read these with care. Plants use different processes and operate under their own approvals, so the right comparison for any plant is its own history and its own limits, not the other plants. Annual averages also hide daily variation: Bonnybrook's flow ranged from winter days near 371,000 m³ to a peak of about 720,000 m³ on 22 July 2025. The treatment steps behind the numbers are described in Calgary's wastewater treatment plants.

03 /How is Calgary's wastewater tested for COVID, flu and RSV?

Samples of wastewater collected at treatment plants are tested for the genetic material of viruses shed by people in the area the plant serves. The University of Calgary describes the provincial program as beginning in 2020, tracking COVID-19 in Alberta municipalities by testing wastewater for genomic traces of the virus, then expanding to influenza, RSV and other pathogens. It says the program is now managed by Alberta Health and Alberta Precision Laboratories and that results are shared on the Centre for Health Informatics dashboard. Since 2023 the work has also included substances of potential abuse, such as opioids.

Calgary also appears in federal reporting. The Government of Canada's national wastewater monitoring dashboard covers COVID-19, flu, RSV and mpox, presents most results as weekly averages, and lists Calgary among the cities added to its joint collection program in 2024.

• Trend over level: a rising line over two or three weeks means more than any single week's value.
• Sewershed, not neighbourhood: each plant serves a large area, so a signal cannot be pinned to a street.
• Dilution matters: rain entering the sanitary system dilutes samples, and many programs adjust results to account for it.
• Lag and revision: laboratory processing takes days, and recent points can change as data are finalized.

04 /What do the service line records add?

They describe the network itself. The City's *Public Sanitary Service Lines* dataset records the public segment of every residential and small-building connection: 367,397 lines with a median install year of 1995. Material codes tell the story of Calgary's growth, from records coded OTHER before the mid-1950s, through a clay tile era that peaked in the 1970s, to PVC from the 1980s on.

Two rules apply every time these numbers are used. The records stop at the property line, so they say nothing reliable about the owner's segment, which may be a different material laid in a different year. And four of its codes, TIL, TP, PLA and OTHER, are not defined in the City's metadata. The Community Sewer Atlas summarizes the records by community, and how to read Calgary's service line records walks through every field.

05 /What about flow in the sewer pipes themselves?

The City has published historical in-pipe measurements. Its *Collection System Levels and Flows* dataset contains data collected in the sanitary sewer system by area-velocity open-channel flow meters, with raw and edited level, velocity and flow values and a flag for finalized, quality-checked records. The metadata describe it as seasonal data, typically May to September, covering 2005 to 2013 with no 2006 data, and warn that the CSV download is about 4.58 GB.

Datasets like this are what engineers use to size pipes and find where rain gets into the sanitary system. For homeowners, the practical lesson is the same one the plant flows teach: wet weather raises sanitary flows, and the defects that let water in are often in private service lines as well as public pipes. Sanitary vs storm sewers in Calgary explains the mechanism.

06 /How can residents use this data responsibly?

1. Cite the source and date

   Name the dataset, the publisher and the date you retrieved it. The City's open data is published under its open data terms of use.

2. Keep the limits attached

   Say that service line figures cover only the City-owned portion, that virus data are community-level trends, and that effluent values vary by plant and day.

3. Avoid false precision

   Round flows and concentrations, and do not rank plants or communities on a single number.

4. Report errors

   If you find a record that looks wrong, such as a material code on your own service line, the City invites corrections through 311.

If you are curious about your own connection rather than the city as a whole, start with the Service Line Lookup. If the record shows an older material and you want your private side checked, you can request quotes for a camera inspection.

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