By OpenStats · Built from official Canadian sources
Direct municipal dataWater quality grade
Fair
Graded against Health Canada drinking water guidelines
Ottawa’s 21 mg/L water is moderately soft with low plant lead, but older Gatineau-side and central neighbourhoods still merit NSF 53 filters. Start with Elite carbon for taste; test before upgrading to RO.
OpenStats pick for Ottawa’s 21 mg/L supply — taste, not minerals
Under-sink carbon for Ottawa
NSF 53 lead option in Ottawa
Baseline Ottawa tap water before RO
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Municipal reports cover the plant. A Tap Score kit tests the water at a Ottawa tap for a broader contaminant panel.
Lab kit partner link. We may earn a commission when tracking is active.
Under-sink and RO systems from Waterdrop Canada — a direct brand alternative to marketplace filters.
Waterdrop affiliate link. We may earn a commission.
Ottawa water hardness is 21 mg/L with pH 7.6.
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 Ottawa 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
Britannia Water Purification Plant
West-end plant (c. 1961) at Cassels Street; nominal capacity 360 ML/day. Coagulation, flocculation, sedimentation, filtration, and disinfection; identical process train to Lemieux Island.
Lemieux Island Water Purification Plant
Central plant (c. 1931/1932) on Lemieux Island; nominal capacity 400 ML/day. Shares the Ottawa River source and multi-barrier process with Britannia.
Central system blends both plants into a common network of roughly 3,000 km of watermains with reservoirs and elevated tanks, serving about 90% of Ottawa’s population. Smaller communal well systems serve outlying villages (Carp, Vars, Munster, Richmond area, Greely).
Health parameters meet Health Canada limits; turbidity above the 1 NTU typical target.
One or more parameters exceed a Health Canada drinking water guideline or turbidity 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 | 21 mg/L | No health limit (aesthetic) | Compliant |
| pH | 7.6 | 6.5–8.5 | Compliant |
| Lead | 0 μg/L | ≤ 5 μg/L | Compliant |
| Fluoride | 0.5 mg/L | ≤ 1.5 mg/L | Compliant |
| Chlorine (free) | 0.5 mg/L | ≤ 4 mg/L | Compliant |
| Turbidity | 3.3 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
Ottawa’s 21 mg/L water is moderately soft with low plant lead, but older Gatineau-side and central neighbourhoods still merit NSF 53 filters. Start with Elite carbon for taste; test before upgrading to RO.
As an Amazon Associate, OpenStats earns from qualifying purchases.
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