By OpenStats · Built from official Canadian sources
Direct municipal dataWater quality grade
Fair
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 Toronto tap for a broader contaminant panel.
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Toronto water hardness is 121 mg/L with pH 7.5.
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 Toronto 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
R.C. Harris Water Treatment Plant
Largest Toronto plant (Queen Street East); conventional treatment, rated capacity 950,000 m³/day. Opened 1941; Art Deco complex often called the Palace of Purification.
R.L. Clark Water Treatment Plant
West-end plant at Twenty Third Street; rated capacity 615,000 m³/day.
F.J. Horgan Water Treatment Plant
East-end plant at Copperfield Road (opened 1979); rated capacity 800,000 m³/day; also supplies Region of York.
Island Water Treatment Plant
Centre Island direct-filtration plant; rated capacity 440,000 m³/day. Supports Enwave deep lake water cooling with cold treated water heat exchange.
Four plants feed 18 pumping stations, 11 underground reservoirs, four elevated tanks, roughly 540+ km of trunk watermains and 5,500+ km of distribution mains across six pressure zones (13 pressure districts). Also delivers water to southern York Region.
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 | 121 mg/L | No health limit (aesthetic) | Compliant |
| pH | 7.5 | 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 | 3.8 NTU | ≤ 1 NTU (typical target) | Exceeds guideline |
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Toronto’s plant lead average is low, but thousands of homes still have lead service lines — your tap can differ. OpenStats recommends NSF 53 filtration (Frizzlife under-sink or Brita Elite) plus a VARIFY kit to test your own address before buying RO.
As an Amazon Associate, OpenStats earns from qualifying purchases.
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