Popular searches
Quick links
Terrebonne's tap water comes from the Rivière des Mille Îles and is treated by the Régie d'aqueduc intermunicipale des Moulins (RAIM), which also serves Mascouche. The RAIM's latest published analysis, from 2026, measured 52 mg/L of total hardness. That is soft water, below the 60 mg/L line. It is a single sample rather than an annual average, so it gives a snapshot. A small sector, Carrefour des Fleurs, gets its water from Repentigny's plant, and this figure does not cover it. In Terrebonne, odours and residue are a bigger worry than scale.
Data last reviewed October 24, 2026.
Terrebonne ranks #10 softest of 31 cities in the Canadian Hard Water Report 2026. See the full ranking
In other units
Source: Régie d'aqueduc intermunicipale des Moulins (RAIM), Analysis results, May 13, 2026 (in French). Data for: May 2026, one published sample. Checked October 24, 2026.
Scale builds slowly with soft water. Odours, grease and detergent residue are the bigger issue, so clean the dishwasher and the washer about every two weeks.
At this hardness, grease and detergent residue are the bigger issue, so start with the dishwasher.
Only dishwashers with a built-in water softener have a hardness setting. Here is the setting for this water, worked out from each maker's own table.
| Brand | Setting |
|---|---|
| Bosch and ThermadorCanadian models with a softener. H:00 is off. | H:00 |
| GaggenauSame ranges as Bosch. The display shows the °E band. | 0-8 |
| MieleSet in °dH. Below 5, Miele says no salt is needed. | 3 |
| Fisher & PaykelDishDrawer models with a softener. 0 is off. | 0 |
Most North American dishwashers, including Bosch models sold in the United States, have no water softener and no hardness setting. With those, use rinse aid and run a dishwasher cleaner once a month.
Sources: Bosch SHX78CC5UC manual, Thermador DWHD661EFP manual, Gaggenau DF481701 manual, Miele dishwasher manual (Canada), Fisher & Paykel DishDrawer guide
Softeners take hardness in US grains per gallon: the figure in mg/L divided by 17.12, rounded up.
| Brand | Setting |
|---|---|
| Nespresso Essenza PlusHardness level, and cups between descalings | Level 0 (4,000 cups) |
| Jura E8Hardness setting | 3 °dH |
Sources: Nespresso Essenza Plus manual, Jura E8 manual, Breville Barista Touch manual, De'Longhi descaling FAQ, Keurig descaling page
Hard water leaves scale on the heating element and the drum, and more detergent residue behind.
Dissolves grease, detergent residue and limescale buildup, and removes odour-causing buildup.
Clears grease, limescale and odour buildup
Breaks down residue and odour-causing buildup inside your washer.
Removes odour and buildup from the drum and hoses
We use the U.S. Geological Survey scale, in mg/L as CaCO₃.
Utilities usually report hardness in mg/L as calcium carbonate (CaCO₃), which is the same as ppm. Dishwasher and softener manuals often use grains per gallon or German degrees instead. Here is how they convert:
No. The RAIM, which treats Terrebonne's water, published a result of 52 mg/L in 2026. That is soft water, under the 60 mg/L line. Water counts as hard above 120 mg/L.
Mostly from the Rivière des Mille Îles. The RAIM draws water from the river, treats it at its plant in Terrebonne and supplies Terrebonne and Mascouche. A small sector, Carrefour des Fleurs, is supplied by the City of Repentigny's plant instead, and this page has no figure for it.
Quite close. Laval's Sainte-Rose plant, which also takes its water from the Rivière des Mille Îles, averaged 61 mg/L in 2025, and the RAIM's 2026 result for Terrebonne was 52 mg/L.
Less often than in harder-water cities. Scale builds slowly with soft water. Grease, detergent residue and odours build up in dishwashers and washers whatever your water, so cleaning the dishwasher and the washer about every two weeks still makes sense.
For dishwashers with a built-in water softener, each maker's table gives: RAIM plant (Rivière des Mille Îles): Bosch and Thermador H:00, Gaggenau 0-8, Miele 3, Fisher & Paykel 0. Most North American dishwashers, including Bosch models sold in the United States, have no water softener and no hardness setting. With those, use rinse aid and run a dishwasher cleaner once a month.
RAIM plant (Rivière des Mille Îles): 4 grains per US gallon (rounded up).
RAIM plant (Rivière des Mille Îles): 3.0 grains per US gallon, or 3.6 grains per imperial gallon.
Régie d'aqueduc intermunicipale des Moulins (RAIM), Analysis results, May 13, 2026 (in French). Data for May 2026, one published sample. We update this page when a new report comes out.
Writing about water in Terrebonne? Copy this code into your site's HTML. The badge links back to this page and its sources.
Your cart is empty.
Shop cleaners
