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Drinking Water Quality and Supply

Toronto Drinking Water Quality

By OpenStats · Built from official Canadian sources

Direct municipal data
C

Water quality grade

Fair

Graded against Health Canada drinking water guidelines

Lead within guidelinepH in range
Hardness vs provincial average157 mg/L · prov. avg 180 mg/L
Lead vs provincial average0.5 μg/L · prov. avg 0.4 μg/L
Hardness
157 mg/L
Lead
0.5 μg/L
≤ 5 μg/L
pH
7.5
6.5–8.5 range
Hardness
157 mg/L
Hard
Lead
0.5 μg/L
Max: 5 μg/L
pH
7.5
6.5–8.5
Chlorine
1 mg/L
Max: 4 mg/L

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Reading this page

Toronto's drinking water earns Grade C (Fair). Hardness is 157 mg/L (hard), and pH is 7.5 against Health Canada's 6.5–8.5 guideline.

Lead at 0.5 μg/L is below the 5 μg/L maximum, and fluoride is 0.6 mg/L against a guideline of ≤ 1.5 mg/L.

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

Supply and treatment

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.

Source type

Surface water

Research confidence: high

Source waters

  • Lake Ontario

Treatment plants

  • 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.

Distribution

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

Compared to provincial average

Ontario · 123 cities in sample

Hardness (city vs Ontario avg)157 mg/L
pH (city vs Ontario avg)7.5
Lead (city vs Ontario avg)0.5 μg/L
Fluoride (city vs Ontario avg)0.6 mg/L

Provincial average: hardness 180 mg/L · pH 7.5 · lead 0.4 μg/L · fluoride 0.6 mg/L

Full parameters

ParameterReadingHealth Canada guidelineStatus
Hardness157 mg/LNo health limit (aesthetic)Compliant
pH7.56.5–8.5Compliant
Lead0.5 μg/L≤ 5 μg/LCompliant
Fluoride0.6 mg/L≤ 1.5 mg/LCompliant
Chlorine (free)1 mg/L≤ 4 mg/LCompliant
Turbidity3.8000000000000003 NTU≤ 1 NTU (typical target)Exceeds guideline
Alberta water licences

WaterRegister.ca

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.

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Source · ECCC / municipal open data (seed). Last updated 2026-09-01. Refreshed on the site's automated schedule.