Hard water and scale: is your area affected?
In short
Hardness measures the amount of dissolved calcium and magnesium in water, expressed in milligrams per litre of calcium carbonate. Below 60 mg/L water is considered soft, 60 to 120 moderately hard, 120 to 180 hard, and above that very hard. Hard water is not a health hazard: it scales plumbing, reduces soap effectiveness and shortens appliance life. Values published by cities in our service area mostly fall in the soft to moderately hard range.
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How to recognise hard water
The signs are mechanical before they are visual: soap and shampoo lather poorly, laundry comes out rough, skin feels tight after a shower. Then come the whitish deposits on fixtures, dishes and shower walls.
The costliest part is invisible. Scale builds up in the water heater and on the heating elements of dishwashers and washing machines, where it acts as an insulator: the appliance draws more energy for the same result, and wears out faster.
Reading your municipality's hardness
Cities that distribute drinking water publish an annual water quality report. Hardness appears in mg/L of CaCO3, sometimes broken down by sector when the network draws on several sources.
In our service area, Terrebonne published a hardness of about 52 mg/L, placing it in the soft category. Laval, supplied by three plants, publishes values near 50.9, 50.3 and 61.3 mg/L depending on the sector — soft, at the edge of moderately hard.
These figures often surprise people: in Quebec, contrary to a widespread belief, much of the south supplied by rivers receives fairly soft water. It is groundwater, the water of wells, that is generally hardest.
We publish no value for municipalities that do not release one. Estimating a city's hardness from its neighbour's would be worthless: that is what the water test is for.
What reverse osmosis does, and does not do, about scale
The membrane retains most calcium and magnesium: water from the dedicated faucet is very soft. That solves taste, kettle deposits and spots on hand-washed glasses.
But a reverse osmosis system treats one point of use. Your water heater, dishwasher, washing machine and showers keep receiving the mains water as it is. If your problem is scale throughout the house, you need a softener installed on the water inlet.
On very hard water, hardness also affects the system itself: it fouls the membrane faster and shortens its life. That is why a softener is sometimes installed upstream of reverse osmosis.
A useful clarification
- Hard water poses no health risk. Calcium and magnesium are minerals, not contaminants. Selling hardness treatment as a health issue is misleading.
- If your water is soft — which is the case across much of our river-supplied service area — a softener will do nothing for you. Check your city's annual report before buying anything.
- We do not install softeners. If your test shows that is what you need, we will tell you rather than sell you a reverse osmosis system that will not solve the problem.
Frequently asked questions
The usual scale places soft water below 60 mg/L of calcium carbonate, moderately hard between 60 and 120, hard between 120 and 180, and very hard above 180 mg/L.