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London Drinking Water Quality
By OpenStats · Built from official Canadian sources
Direct municipal dataB
Water quality grade
Good
Graded against Health Canada drinking water guidelines
Lead within guidelinepH in range
Hardness vs provincial average119 mg/L · prov. avg 182 mg/L
Lead vs provincial average0.4 μg/L · prov. avg 0.4 μg/L
Hardness
119 mg/L
Lead
0.4 μg/L
≤ 5 μg/L
pH
7.3
6.5–8.5 range
Hardness
119 mg/L
Moderate
Lead
0.4 μg/L
Max: 5 μg/L
pH
7.3
6.5–8.5
Chlorine
0.9 mg/L
Max: 4 mg/L
From source to sink
Where London water comes from
Lakes, rivers, wells, and treatment plants behind the kitchen tap, in plain language. Chemistry grades above are a separate lab snapshot; this section is the route the water travels.
Open the full tap storyOn the map
Where London water lives
Source waters and treatment plants pinned from published utility names. Open a pin below for the full OpenStreetMap view.
- CityLondon
Municipal service area
- Source waterLake Huron
Lake Huron supply corridor
- Source waterLake Erie
Source water
- Treatment plantLake Huron Primary Water Supply System Water Treatment Plant
Approximate pin near London (exact plant coordinates pending)
- Treatment plantElgin Area Primary Water Supply System Water Treatment Plant
Approximate pin near London (exact plant coordinates pending)
Map data © OpenStreetMap contributors. Pins are approximate for orientation, not legal survey points.
Where it starts
Surface water
Research confidence: high
Named source waters
- Lake Huron
- Lake Erie
Treatment plants
Lake Huron Primary Water Supply System Water Treatment Plant
Regional plant north of Grand Bend treating Lake Huron water for London and other member municipalities. Board-owned; OCWA-operated; capacity about 340 ML/day.
Elgin Area Primary Water Supply System Water Treatment Plant
Regional plant east of Port Stanley treating Lake Erie water. Board-owned; OCWA-operated; capacity about 91 ML/day. Water reaches London via the Elgin-Middlesex Pumping Station.
How it reaches your street
City of London owns and operates the local Drinking Water System (Class IV distribution / Class II treatment rating for city assets) with more than 2,100 km of pipes, reservoirs, and pumping stations. Regional boards supply bulk treated water; London is administering municipality for the Lake Huron board.
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Reading this page
London's most recent drinking water sample (2026-07-22) reports hardness of 119 mg/L, classified as moderately hard, and pH 7.3, drawn from a mixed water source and treated at London Water Treatment Plant. Lead measured 0.4 μg/L and fluoride 0.7 mg/L.
Free chlorine measured 0.9 mg/L in this sample. No E. coli was detected in this sample.
London's hardness of 119 mg/L is below the Ontario average of 182 mg/L across 51 tracked municipalities, with a provincial average pH of 7.5.
These readings summarize a single compliance snapshot, not a certification of the water reaching your tap. Test your own water periodically, especially on a private well, and consider a softener if hardness is classified hard or very hard.
How to use this page: read the headline metrics first, then where the water comes from (map and tap story), then the parameter table and source footer.
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 · From source to sink
How drinking water reaches your tap
Compared to provincial average
Ontario · 51 cities in sample
Hardness (city vs Ontario avg)119 mg/L
pH (city vs Ontario avg)7.3
Lead (city vs Ontario avg)0.4 μg/L
Fluoride (city vs Ontario avg)0.7 mg/L
Provincial average: hardness 182 mg/L · pH 7.5 · lead 0.4 μg/L · fluoride 0.6 mg/L
Full parameters
| Parameter | Reading | Health Canada guideline | Status |
|---|---|---|---|
| Hardness | 119 mg/L | No health limit (aesthetic) | Compliant |
| pH | 7.3 | 6.5–8.5 | Compliant |
| Lead | 0.4 μg/L | ≤ 5 μg/L | Compliant |
| Fluoride | 0.7 mg/L | ≤ 1.5 mg/L | Compliant |
| Chlorine (free) | 0.9 mg/L | ≤ 4 mg/L | Compliant |
| Turbidity | 2.1 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.
Explore WaterRegister.ca →Drinking water filters and test kits
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Source · Huron Erie Water (Lake Huron and Elgin Area primary supply) consumer FAQ. Last updated 2026-07-22. Refreshed on the site's automated schedule.