Water hardness in St. Catharines
134 mg/L hard
Tap water in St. Catharines is hard: 134 mg/L (7.8 gpg · 7.5 °dH · 13.4 °fH).
Source: Ontario Ministry of the Environment, Conservation and Parks, Drinking Water Surveillance Program, Open Government Licence – Ontario (2015) · data checked 2026-10-21
This figure is over 3 years old; hardness may have changed.
St. Catharines is served by the Niagara Region's Decew Falls plant, which treats Great Lakes water. The surveillance programme reported 134 mg/L as CaCO3 for 2015, with no range published. The reading is hard, and visible scale on kettles is common.
Health Canada: hardness above 200 mg/L is considered poor but tolerable; above 500 mg/L unacceptable.
Water data
| Total hardness | 134 mg/L |
|---|---|
| Utility | Decew Falls-Niagara Falls Drinking Water System - Decew Falls |
How St. Catharines compares
- Tap water in St. Catharines is 32 % harder than the median of the 254 cities we track in Canada (101 mg/L).
- By hardness it ranks 70 of 254 in Canada (1 = hardest); 72 % of these cities have softer water.
- In Ontario it is number 40 of 120 cities; the regional median is 124 mg/L.
- Nearest city with clearly softer water: Peterborough, 146 km away (95 mg/L).
- Nearest city with clearly harder water: Milton, 64 km away (222 mg/L).
Ranking of the hardest and softest water in Canada →
What it means at home
- Fast scale on taps, shower screens and kettle; white spots on glassware.
- Water heater: efficiency loss and element failures within years if unprotected.
- Dry skin and dull hair after showering are common.
- Softener recommended; jug or reverse osmosis for drinking.
How much salt will you use for softening?
Recommended, especially with a heater or boiler: scale cuts efficiency and shortens its life.
Descale a coffee machine or kettle about every 2 months (typical manufacturer guidance for this hardness).
Estimates for planning, not a quote. Check your appliance manual for exact settings.
Dishwasher setting in St. Catharines
| Brand | Setting for this water |
|---|---|
| Bosch | H01 |
| Miele | 8 °dH |
| AEG / Electrolux | 2 |
| Beko | 2nd |
| Hoover | S1 |
| LG | H2 |
From each brand's manual for the model family named in the source; your model may differ, so check its manual. All brands and how to change the setting →
FAQ
Is St. Catharines water hard or soft?
It is hard: 134 mg/L as CaCO₃ (7.8 gpg, 7.5 °dH). The usual bands are soft < 60, moderately hard 60–120, hard 120–180 and very hard > 180 mg/L.
Is tap water in St. Catharines safe to drink?
Hardness is not a health issue; it is about limescale, taste and appliances. Mains water must meet national drinking-water standards. Health Canada: hardness above 200 mg/L is considered poor but tolerable; above 500 mg/L unacceptable.
How many grains per gallon is St. Catharines water?
7.8 gpg, equal to 7.5 °dH, 13.4 °fH or 134 mg/L calcium carbonate.
What dishwasher salt setting should I use in St. Catharines?
For 134 mg/L (7.5 °dH) check your manufacturer's table: level 4–5.
Do I need a water softener in St. Catharines?
Recommended if you have a water heater, boiler or tankless unit: it saves repairs and detergent.
Source
Source: Ontario Ministry of the Environment, Conservation and Parks, Drinking Water Surveillance Program, Open Government Licence – Ontario (2015). Method: figure published by the water supplier. Ontario Ministry of the Environment, Conservation and Parks, Drinking Water Surveillance Program, Open Government Licence – Ontario · Outdated figure? Tell us