The wastewater service surcharge is billed in addition to regular sewer service charges when our lab tests show that a business is releasing over-strength wastewater into the sewer system. This surcharge appears as a separate item on your utility statement.

How is the wastewater surcharge calculated?

Businesses on the surcharge program have their wastewater sampled and tested on two separate days and the average strength from the two tests is used to create a surcharge factor given in cents-per-cubic-meter.

This surcharge remains in place for a minimum of three months. After this period, we collect new samples, analyze the concentration, and calculate another surcharge factor.

This surcharge factor replaces the previous one and is used to create the monthly surcharge, which multiplies the water consumption of the facility by the new surcharge factor.

Learn more about the testing process and calculation of the Wastewater Surcharge:

Commercial wastewater monitoring

The City of Calgary monitors wastewater coming from commercial water customers for prohibited, restricted, and surcharge parameters. We collect samples from test manholes near the business and submit them to our Bonnybrook lab for analysis.

We list the limits for contaminants in Schedule A of the Wastewater Bylaw. Our testing is done by our ISO 17025 lab which handles more than 400,000 tests a year.

Steps for sampling wastewater

We collect either a discrete grab sample or 24hr composite samples by using an autosampler.

We place the autosampler in manholes to get a sample of the wastewater going into the sewer system. The autosampler takes samples over a 24-hour period.

For grab sampling, we take a small sample as it is flowing into the manhole. Any sample we take from a place's water as it flows into the sewer system can be used to see if the water meets the bylaw.

What about shared manholes?

If there are several water sources going into one manhole, we use the sample for all places putting water into that shared manhole.

If testing shows that water going into that manhole has over-strength wastewater, we bill a wastewater surcharge in addition to regular sewer charges to a business. For shared manholes, we bill the surcharge to all places releasing wastewater into that manhole.

Exemptions to the Surcharge Program

There are exceptions to the surcharge, including metered water used only for irrigation systems, and water used by a business that is not flowing into the sewer system.

For the latter, this water must be measured by a meter, which is installed, maintained and repaired by the business asking for an exemption.

We also offer an Effluent Metering Program for businesses that use a large amount of water, but return much less back as wastewater. For these businesses, an effluent meter may be a more accurate way of measuring and billing the amount of wastewater they create.