Microplastics are in the Outaouais' water, from the river to the tap

Tashi Farmilo

Microplastics are in the Ottawa River, in Gatineau's tap water, and almost certainly in the people drinking it. That was the message at a June 11 webinar, the first public session of this year's Mois de l'eau, the annual education campaign that runs through June across Quebec's watershed organizations.

Hosted by the Agence de bassin versant des 7 (ABV des 7), the session paired two local researchers under the title "Microplastiques en Outaouais: de l'eau potable à la rivière." The 2026 edition of Mois de l'eau, coordinated provincially by the Regroupement des organismes de bassins versants du Québec, has taken microplastics as its theme, and the Outaouais sits near the centre of the story. A large share of Quebecers draw their drinking water from the Ottawa River or the St. Lawrence, and the Ottawa-Gatineau corridor is where local contamination runs heaviest.

The first speaker, Catherine Hallé, is a biology teacher at the Cégep de l'Outaouais and co-coordinator of its environmental health and biodiversity research centre, SEBO. She walked through what microplastics are, plastic fragments between roughly one micron and five millimetres, sometimes visible and often not, along with the even smaller nanoplastics that can slip inside living cells. The science is young. Researchers only flagged microplastics as a problem in 2004, and most findings about plastic in human blood, the placenta and the brain have emerged since 2020. Hallé did not overstate the danger, noting that strong evidence on health effects remains thin, though some studies point to a weakened immune system.

What is settled is that the particles are everywhere, and that the largest source of human exposure is not water, but the dust people breathe indoors from synthetic clothing and furnishings. Ingestion through food, beverages and packaging comes next. Hallé also flagged a counterintuitive finding from her own lab: bottled water and even new plastic products shed particles without obvious wear, and a small test with a plastic kettle showed measurable increases after water sat in it for as little as five to fifteen minutes.

Her three-year project, running from 2024 through 2027 with the City of Gatineau, is the first attempt to put numbers to the local picture. Working with Sanaz Safa of the CEPROCQ and Université de Montréal chemist Sébastien Sauvé, the team is characterizing microplastics in the city's wastewater and drinking water. No local figures are published yet, but early observations are clear. Wastewater is full of microplastics, treatment plants remove the large majority, in the range of 90 to 98 per cent based on studies elsewhere, and a fraction still gets through. Drinking water, sampled in one Gatineau sector chosen for methodological reasons, contains them too, as it does everywhere tested. One early surprise was an abundance of PLA, the bioplastic used in 3D printing, alongside the usual polyethylene and PET.

The second presenter, Larissa Holman of Ottawa Riverkeeper, the Garde-rivière des Outaouais, set the wider context. Her group's work with Carleton University researcher Jesse Vermaire, first released in 2016, relied on citizen volunteers collecting more than 60 hand-filtered and trawl samples across a river that runs 1,270 kilometres through a basin roughly twice the size of New Brunswick. Microplastics turned up in every sample, even far upstream where almost no one lives, and most were microfibres shed from clothing. The particles act, as Vermaire put it when the study came out, "kind of like a sponge," soaking up other contaminants in the water. Concentrations were highest in the Ottawa-Gatineau area and near wastewater outfalls. Sediment sampling along the shorelines found no significant buildup, which the researchers attribute to the river's heavy spring and fall flooding pushing contaminants downstream.

Both speakers landed on the same point. There is no clean fix, because the particles are already everywhere, but reducing plastic consumption is the place to start. Hallé recommended cutting synthetic textiles, avoiding glitter and single-use items, disposing of waste properly, and installing an inexpensive laundry filter to catch fibres before they reach the sewer. She also had reassurance for the tap, calling Gatineau's drinking water excellent and free, and a better bet than bottled water on several counts. The urgency, she said, comes from how new the field still is, a science only now taking shape even at the global scale.