‘Once you notice the smell, you can’t not notice it’: Why some find Durham’s stinky water tough to swallow

The culprit behind the region’s smelly tap water is the die-off of seasonal algae in Lake Ontario.

Thestar.com
Sept. 7, 2022
Noor Javed

The water just didn’t taste right.

Soon after moving to Pickering, resident Zeeshaan Mustafa noticed the tap water at his home had a “different” odour and taste than what he was used to in Toronto. And over the summer, its aroma became more distinct.

“When you turn on the tap, and especially hot water, there’s a musty almost earthy smell,” said Mustafa, who moved to Durham Region in December.

“The problem is, once you notice the smell, you can’t not notice it. It’s always there,” he said.

Mustafa’s observations were validated in August, when Durham Region sent an advisory to its residents telling them not to worry if their water had an “earthy or musty” odour to it and assured them that it was still safe to drink.

Durham Region may have gone public with its seasonal stinky water problems, but it’s not the only GTA city to have them. While Durham received 36 water-related calls in August, the city of Toronto said it has also received around 160 “calls for taste and odour” since the beginning of August, down from last year.

The culprit behind the smell is a relatively benign compound which can pass through conventional treatments and be detected by the most sensitive of palates. But it’s difficult to plan for and has scientists investigating if its resurgence may be related to warming lakes and climate change.

“This happens when there is naturally occurring algae in the lake, and the water temperature goes up,” said William Fernandes, director, water treatment and supply, with the city of Toronto, who calls it a “seasonal thing.”

While Lake Ontario serves as the main drinking water source for most GTA-area communities, the odour is evident mostly in the late summer/early fall when algae blooms take place. When the seasonal algae dies off, it releases chemicals called geosmin and 2-Methylisoborneol (2-MIB) -- naturally occurring compounds in Lake Ontario and Lake Simcoe -- which humans can detect at even trace amounts. According to one estimate, if you poured a teaspoon of geosmin into 200 Olympic-sized swimming pools, you could still smell it.

While not harmful, the presence of the chemical can impact the “esthetic” of the water -- producing the distinct flavour that can range from musty to swamplike.

“The die-off can happen in one place, but the compounds can occur lakewide as they can move and shift with lake currents, wind and weather,” said Tavis Nimmo, a supervisor in the works department in Durham Region.

But other factors such as the location and depth of water intake pipe from the lake, and slight variations in regional water treatment process can also impact the flavour of the water, which means that depending on where you live in the GTA -- or even within the same city -- you may have a very different tap water drinking experience.

“An algae bloom may be present at one water source and not others, even within the same lake,” said October S. Bell, supervisor of the water and wastewater compliance for Peel. “The Region of Peel’s two Lake Ontario water treatment plants are only 6 kilometres apart, but sometimes only one will experience an algae event.”

Nimmo said that at the newest water plant in Ajax built in 2000 along Lake Ontario, the intake pipe was situated 2.5 km out from shore and 18 m deep. The other four Durham plants along Lake Ontario are in the “nearshore area” and only go out a kilometre away from shore and are around 10 m deep.

He said the Ajax plant sees the lowest amount of taste and odour compounds in the water, as compared to the other four. The Ajax plant also has a mechanism to add granular activated carbon (GAC) -- basically a giant Brita filter -- which can help remove the odorous residue.

Nimmo said planned plant upgrades at two other Durham plants will incorporate various odour-reducing treatments.

Peel Region, which also provides water to much of York Region, already uses a variety of treatment measures like granular activated carbon and an advanced oxidation ultraviolet process.

Fernandes said that Toronto has four water treatment plants, but they don’t actively tackle the odour issue as “it takes some time and effort” to introduce odour-killing technologies.

Between the time they receive complaints, and begin the process to fix it, the “event” is already over.

“It’s a moot point to do it at that point,” he said.

Each day, the city of Toronto treats more than 1 billion litres of safe drinking water at four water treatment plants. Toronto tests water quality every six hours, and conducts thousands of tests every year at different points in the treatment plants and in the distribution system.

During the summer months, the water is also tested for the presence of geosmin and 2-MIB weekly.

According to Andrea Kirkwood, an associate biology professor at Ontario Tech in Durham, the algae blooms that cause the malodorous water are different than the algae that chokes shorelines causing a pungent smell.

“There are the many different types of algal blooms: you have Cladophora blooms that are on the Ajax-Pickering shoreline that cause stink from decomposing, then you have harmful algal blooms like we have seen on Lake Erie,” said Kirkwood, who specializes in algae. “But this is from a natural causing algae ... which can get into our drinking water but is not toxic.”

It also has no connection to the bacteria, like E. coli, that have been responsible for beach closures in Durham this summer, she said. Bacteria are filtered out by municipalities in their extensive water treatment process.

Kirkwood is also a resident of Whitby and also noticed that her tap water had a funny taste this month -- similar to what she recalls drinking in Ontario as child -- and assumed it had to do with an issue at a treatment plant.

She said it's difficult to know definitively what causes odour-inducing blooms, since they can be produced by different types of algae, but conditions such as storms and fluctuating water temperatures can play a role in creating ideal conditions.

While climate change has been touted as one reason for warming lakes, Kirkwood said that the evidence is not clear cut that it is also responsible for the odour-causing algae blooms.

Nimmo said that for Durham residents, the complaints about odd-tasting water are not just a summer thing.

“We get a lot of calls from people who live in Toronto and work in Durham, or move to Durham about this,” he said. “The biggest complaint we get is, ‘why does my water taste and smell like a swimming pool, but it doesn’t in Toronto?”

Nimmo said in Durham the water is treated primarily with chlorine as a disinfectant to remove bacteria, algae and viruses from the lake water.

In Toronto, water is treated with chlorine and ammonia (among many other chemicals), which ensures that the chlorine levels remain consistent as water travels through the city’s complex and extensive water distribution system all the way to southern York Region.

But Nimmo said despite the differences between the two, both treatments are safe and effective. Moreover, he stresses that filters are not necessary, and drinking from the tap is safe.

Mustafa said that even with the Region’s reassurance, the smelly water is difficult to swallow. “It’s gotten to the point that I recently called up a water company to find out the cost of adding a filter,” he said.

Recently, Durham Region issued a warning to residents to be wary of high-pressure sales pitches for water filtration and treatment equipment, emphasizing that the sales were not endorsed by the region.

And if you can’t stomach the taste? The experts have a simple solution: mask it.

“Fill a jug and put it in the fridge or put some ice cubes in it or get extra fancy and add some lemon wedges or cucumber slices,” said Fernandes. “It does the job.”