Why Calgary's drinking water is tasting icky

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You may wonder why your water is suddenly tasting mouldy.

This unpleasant taste may follow you into the shower, your workplace, gym or college campus. You may have also been losing sleep over thoughts of contaminated water affecting your health.

But the reality is nowhere near as dangerous as it seems.

City officials say the cause of your worry is geosmin, a “harmless” naturally occurring carbon compound that usually makes its way into Calgary’s reservoirs in late summer or fall.

“This can produce a temporary, earthy or musty change to the taste and odour of your water, but it remains safe to drink and continues to meet all guidelines set by provincial and federal health standards,” a city website states.

If only there was a way to convey that to our noses. One estimate shows a human nose can detect the substance at proportions of less than 10 parts per trillion — which amounts to a teaspoonful in 200 Olympic-size swimming pools.

But how does geosmin enter our drinking water in the first place?

Dr. Cathryn Ryan, a professor at the University of Calgary’s Department of Earth, Energy Environment, explains drinking water in Calgary mainly comes from two sources.

The first is the Glenmore Reservoir — built on the Elbow River near Glenmore Trail — which derives more than 95 per cent of its supply from the Bragg Creek in the Rocky Mountains.

The second, called the Bearspaw Reservoir, is constructed along the Bow River, which receives most of its water from creeks above Exshaw, a hamlet west of Calgary.

“We’re very fortunate that our water supply comes from the mountains, which doesn’t have very much development on it,” Ryan added.

But as water levels fall during the summer, some kinds of algae and bacteria present in the reservoirs can naturally produce compounds like geosmin.

We aren’t entirely unfamiliar with it. “For instance, if you walk outside after it’s rained for the first time in a long time and it smells earthy, that’s geosmin,” Ryan said.

Geosmin is hardly alone in the water. The reservoir also contains different chemicals that abound in the mountains where our drinking water comes from, including sodium, potassium, calcium bicarbonate and magnesium, some of which are removed after the water is treated at a plant just outside the reservoir.

The liquid from the treatment plant is then sent to pumping stations — nondescript buildings with pumps that connect to the pipes feeding us water.

Some harmless chemicals, such as geosmin and chlorine (used to disinfect water from bacteria, including E.coli) slip into the treated water. They aren’t removed, Ryan said, because the costs outweigh the potential health benefits.

Other chemicals such as calcium bicarbonate, which is responsible for the white deposits in your glasses, aren’t separated in the treatment process because they are “actually healthy to drink,” Ryan said.

When it comes to disinfecting agents like chlorine, Ryan added that she’d rather consume them than the bacteria they’re designed to kill. “If the city didn’t disinfect our water supply, I wouldn’t drink it,” she said.

“It’s a lot safer to drink disinfected water with disinfection byproducts, than to drink water that isn’t disinfected, because you could have an E. coli outbreak in all of Calgary.”

For those concerned about such chemicals nevertheless, Ryan suggests using a charcoal filter commonly found in department stores.

There is nothing the city can do for those bothered by the smell of geosmin other than to emphasize it doesn’t impact one’s health, its concentrations will drop as temperatures fall and squeezing lemon into liquid containers may reduce the odour.

Lead levels

A year-long investigation by more than 120 journalists in 2019 found hundreds of thousands of Canadians were consuming lead, which is deemed a carcinogen, through tap water.

City officials in Calgary said at the time they knew about 550 addresses whose water contained lead, thanks to aging infrastructure. But the investigation found many homes in the city that weren’t on the list but whose water bore traces of the carcinogen.

The investigation sparked various council meetings where councillors openly admitted they hadn’t adequately “quantified” the problem.

Later, the city, through its Accelerated Lead Removal Program in 2020, found 695 addresses that were receiving lead in their water, 545 of which were public, and the remaining 150 were private.

Experts agree lead doesn’t occur in the reservoirs but in the service lines that deliver drinking water to homes.

“The only way for lead to be found in the water is for it to be picked up in the distribution system via public and private water service lines,” read a statement by the city to Postmedia.

The issue is mainly concentrated in inner-city dwellings, the majority of which were built in the 1950s.

Their water service connections primarily used lead between 1939 and 1947 — during the Second World War — when copper was not readily available

The city told Postmedia in a statement that 290 of those lines have been replaced, and 45 will be phased out by the end of 2023.

“An additional 66 will be replaced as contractors become available and whenever possible, in coordination with other water infrastructure work in the same area,” the statement read.

“The city is responsible for the water service line that extends from the water main up to the property line.

“The homeowner is responsible for the service line on private property, as well as all pipes, plumbing and fittings within their home.”

The final cost for replacing an affected private water service line is $3,500 and includes a two-year warranty period. The two ways of doing so are by either paying the city the full amount or adding it to your property taxes and having it paid out over 15 years without any interest.