Tap water hardness in Ontario
We have published hardness data for 120 cities in Ontario. The median is 124 mg/L; the hardest water is in Elora (519 mg/L), the softest in Huntsville (12 mg/L).
60 % of these cities have hard or very hard water (over 120 mg/L).
Health Canada: hardness above 200 mg/L is considered poor but tolerable; above 500 mg/L unacceptable.
Cities in Ontario, hardest first
| mg/L | mg/L | ||
|---|---|---|---|
| Elora | 519 | 519 | very hard |
| Fergus | 519 | 519 | very hard |
| Stratford | 489 | 489 | very hard |
| Kitchener | 454 | 454 | very hard |
| Hanover | 404 | 404 | very hard |
| Woodstock | 392 | 392 | very hard |
| Ingersoll | 376 | 376 | very hard |
| Erin | 369 | 369 | very hard |
| Walkerton | 363 | 363 | very hard |
| Ohsweken | 358 | 358 | very hard |
| Georgetown | 357 | 357 | very hard |
| Orangeville | 337 | 337 | very hard |
| Guelph | 332 | 332 | very hard |
| Manitouwadge | 329 | 329 | very hard |
| Acton | 324 | 324 | very hard |
| Halton Hills | 324 | 324 | very hard |
| Stouffville | 318 | 318 | very hard |
| Whitchurch-Stouffville | 318 | 318 | very hard |
| Mount Albert | 317 | 317 | very hard |
| Brant | 315 | 315 | very hard |
| Midland | 305 | 305 | very hard |
| Tillsonburg | 296 | 296 | very hard |
| Simcoe | 290 | 290 | very hard |
| Caledon | 283 | 283 | very hard |
| Dorchester | 265 | 265 | very hard |
| North Perth | 265 | 265 | very hard |
| Brantford | 261 | 261 | very hard |
| Orillia | 261 | 261 | very hard |
| Delhi | 241 | 241 | very hard |
| Milton | 222 | 222 | very hard |
| Norfolk County | 216 | 216 | very hard |
| Waterford | 216 | 216 | very hard |
| Lindsay | 214 | 214 | very hard |
| Stoney Point/Pointe-aux-Roches | 210 | 210 | very hard |
| Ballantrae | 205 | 205 | very hard |
| Port Rowan | 179 | 179 | hard |
| East Gwillimbury | 168 | 168 | hard |
| Newmarket | 141 | 141 | hard |
| Innisfil | 136 | 136 | hard |
| St. Catharines | 134 | 134 | hard |
| Thorold | 134 | 134 | hard |
| Dunnville | 133 | 133 | hard |
| King City | 131 | 131 | hard |
| Aurora | 130 | 130 | hard |
| Vaughan | 128 | 128 | hard |
| Oakville | 127 | 127 | hard |
| Richmond Hill | 127 | 127 | hard |
| Markham | 126 | 126 | hard |
| Welland | 126 | 126 | hard |
| Amherstview | 125 | 125 | hard |
| Bolton | 125 | 125 | hard |
| Bowmanville | 125 | 125 | hard |
| Brampton | 125 | 125 | hard |
| Brooklin | 125 | 125 | hard |
| Mississauga | 125 | 125 | hard |
| Pickering | 125 | 125 | hard |
| Belle River | 125 | 125 | hard |
| Fort Erie | 125 | 125 | hard |
| Hamilton | 125 | 125 | hard |
| Grimsby | 124 | 124 | hard |
| Brockville | 124 | 124 | hard |
| Chatham | 123 | 123 | hard |
| Cobourg | 123 | 123 | hard |
| Port Hope | 123 | 123 | hard |
| Port Colborne | 123 | 123 | hard |
| Burlington | 122 | 122 | hard |
| Quinte West | 121 | 121 | hard |
| Kingston | 120 | 120 | hard |
| Napanee | 120 | 120 | hard |
| Niagara Falls | 120 | 120 | hard |
| Prescott | 120 | 120 | hard |
| Stoney Creek | 120 | 120 | hard |
| Cornwall | 120 | 120 | moderately hard |
| Toronto | 119 | 119 | moderately hard |
| Willowdale | 119 | 119 | moderately hard |
| Picton | 117 | 117 | moderately hard |
| St. Thomas | 117 | 117 | moderately hard |
| Alexandria | 114 | 114 | moderately hard |
| Belleville | 108 | 108 | moderately hard |
| London | 108 | 108 | moderately hard |
| Windsor | 107 | 107 | moderately hard |
| Amherstburg | 105 | 105 | moderately hard |
| Essex | 104 | 104 | moderately hard |
| Harrow | 104 | 104 | moderately hard |
| Kingsville | 104 | 104 | moderately hard |
| Leamington | 104 | 104 | moderately hard |
| Goderich | 102 | 102 | moderately hard |
| Wallaceburg | 101 | 101 | moderately hard |
| Petrolia | 99 | 99 | moderately hard |
| Sarnia | 99 | 99 | moderately hard |
| Walpole Island | 98 | 98 | moderately hard |
| Port Elgin | 97 | 97 | moderately hard |
| Kapuskasing | 97 | 97 | moderately hard |
| Peterborough | 95 | 95 | moderately hard |
| Dowling | 94 | 94 | moderately hard |
| Owen Sound | 92 | 92 | moderately hard |
| Collingwood | 86 | 86 | moderately hard |
| Renfrew | 86 | 86 | moderately hard |
| Perth | 85 | 85 | moderately hard |
| Smiths Falls | 82 | 82 | moderately hard |
| Wawa | 76 | 76 | moderately hard |
| Sault Ste. Marie | 75 | 75 | moderately hard |
| Dryden | 73 | 73 | moderately hard |
| Moose Factory | 73 | 73 | moderately hard |
| Nipigon | 72 | 72 | moderately hard |
| Greater Sudbury | 65 | 65 | moderately hard |
| Hawkesbury | 65 | 65 | moderately hard |
| Kenora | 52 | 52 | soft |
| Terrace Bay | 47 | 47 | soft |
| Clarence-Rockland | 46 | 46 | soft |
| Thunder Bay | 46 | 46 | soft |
| Gravenhurst | 42 | 42 | soft |
| Kirkland Lake | 39 | 39 | soft |
| Ottawa | 36 | 36 | soft |
| Bracebridge | 33 | 33 | soft |
| Callander | 28 | 28 | soft |
| Elliot Lake | 27 | 27 | soft |
| Fort Frances | 21 | 21 | soft |
| Pembroke | 12 | 12 | soft |
| Huntsville | 12 | 12 | soft |