By OpenStats · Built from official Canadian sources
Direct municipal dataWater quality grade
Good
Graded against Health Canada drinking water guidelines
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Municipal reports cover the plant. A Tap Score kit tests the water at a Markham tap for a broader contaminant panel.
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Markham water hardness is 126 mg/L, from the city's published water quality reporting.
How to use this page: read the headline metric and provincial comparison first, then supply and treatment notes, then the source footer for the underlying dataset.
Watershed to tap
How Markham draws, treats, and distributes drinking water, from municipal and utility publications. Chemistry grades above come from separate parameter records; this section does not invent plant lab figures.
Surface water
Research confidence: high
City of Toronto and Region of Peel treatment plants (wholesale) — York Region supply
Markham receives Lake Ontario water pre-treated by Toronto and Peel under long-term supply contracts. York Region owns the York Drinking Water System transmission, storage, and pumping that feeds Markham’s local distribution system.
York Region delivers purchased treated water through regional reservoirs and pumping stations; the City of Markham operates local watermains, valves, and hydrants to retail customers. Markham’s urban system is lake-based with no local raw-water plant.
Health parameters meet Health Canada limits; turbidity above the 1 NTU typical target.
Health parameters meet Health Canada limits; turbidity exceeds the typical 1 NTU aesthetic target.
Figure 1 · Supply chain
From watershed to tap
Ontario · 123 cities in sample
Provincial average: hardness 178 mg/L · pH 7.5 · lead 0.4 μg/L · fluoride 0.6 mg/L
| Parameter | Reading | Health Canada guideline | Status |
|---|---|---|---|
| Hardness | 126 mg/L | No health limit (aesthetic) | Compliant |
| pH | 7.2 | 6.5–8.5 | Compliant |
| Lead | 0.5 μg/L | ≤ 5 μg/L | Compliant |
| Fluoride | 0.6 mg/L | ≤ 1.5 mg/L | Compliant |
| Chlorine (free) | 1 mg/L | ≤ 4 mg/L | Compliant |
| Turbidity | 3 NTU | ≤ 1 NTU (typical target) | Exceeds guideline |
On a private well or holding an Alberta water allocation licence? Water Register maps EPA licence records, transfer comparables, and watershed context across the province.
Explore WaterRegister.ca →OpenStats pick
Markham pairs 126 mg/L hardness with 1.0 mg/L chlorine — taste and scale show up together. Elite carbon for drinking, shower filter for chlorine, strips so you know when you need a softener.
As an Amazon Associate, OpenStats earns from qualifying purchases.
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