ST. JOHN’S, N.L. – The City of St. John’s, N.L., is advising residents to season their tap water with “lemon or other citrus fruits” to offset a funky, but harmless taste permeating the water supply.

Residents were informed in a statement Wednesday evening that the “earthy” or “musty” odour in the water is not toxic or harmful, and often occurs during the summer months.

The city said the aroma is a result of naturally occurring organic substances in the water supply, and that it can become more potent when the water is boiled.

St. John’s resident Kent Barrett said Thursday that he has noticed a flavour change, but hasn’t really been bothered by similar tastes over the years.

“As long as I can remember, certain times of year the water in town can taste a little ‘pondy,'” said Barrett. “It doesn’t last and I’ve never noticed any ill effect.”

Staff at local restaurants also said there is a noticeable change in the taste of the water.

Sarah Crocker, an environmental technician for Northeast Avalon Atlantic Coastal Action Program, researches the health of the province’s watersheds, including those that supply water to St. John’s.

Crocker said the odour comes from geosmin, an organic compound produced by algae and bacteria as the weather warms up. That makes the phenomenon a somewhat regular occurrence in the warm summer months.

Humans are particularly sensitive to the smell, she said, and trace amounts as small as five parts per trillion are detectable by people drinking the water.

But, Crocker said it’s perfectly safe to drink and is found in things like beets.

“It’s that smell in the soil after a rain. We’re just very sensitive to the smell of this particular bacteria,” Crocker said.

Crocker said the city’s advice about adding lemon slices to the water holds up scientifically. Increasing acidity in the water will decrease the presence of geosmin, so the acidity of a lemon would dilute the strong scent, she said.

The city is unsure how long the taste will remain, but says it could last anywhere from a few days to several weeks.

“Since this is a naturally occurring phenomenon, it cannot be predicted how long it may persist. Past taste and odour events have usually lasted for up to two to three weeks,” Wednesday’s release read.

Crocker said there are other filtration techniques that could lessen the intensity of the semi-regular scent event, but those methods are typically more expensive.

“It is a natural phenomenon, but there are solutions — like using ceramic filtration or even activated charcoal filters — that would address the issue. But the limitation that we face is one of cost, so those solutions are a little bit cost-prohibitive,” said Crocker.

Officials said the water is monitored daily, and thanked residents for their patience during the “taste and odour event.”