Water hardness in Erin
369 mg/L very hard
Tap water in Erin is very hard: 369 mg/L (21.6 gpg · 20.7 °dH · 36.9 °fH).
Source: Ontario Ministry of the Environment, Conservation and Parks, Drinking Water Surveillance Program, Open Government Licence – Ontario (2016) · data checked 2026-10-21
This figure is over 3 years old; hardness may have changed.
Erin relies on groundwater from wells in the limestone-rich Niagara Escarpment area. The programme reported 369 mg/L as CaCO3 for 2016, with no range published. This is very hard water, and scale builds up fast.
Health Canada: hardness above 200 mg/L is considered poor but tolerable; above 500 mg/L unacceptable.
Water data
| Total hardness | 369 mg/L |
|---|---|
| Utility | Erin Drinking Water System |
How Erin compares
- Tap water in Erin is 264 % harder than the median of the 254 cities we track in Canada (101 mg/L).
- By hardness it ranks 9 of 254 in Canada (1 = hardest); 97 % of these cities have softer water.
- In Ontario it is number 8 of 120 cities; the regional median is 124 mg/L.
- Nearest city with clearly softer water: Caledon, 12 km away (283 mg/L).
- Nearest city with clearly harder water: Fergus, 26 km away (519 mg/L).
Ranking of the hardest and softest water in Canada →
What it means at home
- Severe scale: heater elements and washing-machine heaters fail early.
- Detergent use is very high; taps and screens coat within days.
- Dishwasher at maximum salt setting.
- An ion-exchange softener is practically essential; RO for drinking water.
How much salt will you use for softening?
Yes. At this hardness a softener pays for itself through appliance life and detergent.
Descale a coffee machine or kettle about every 1 months (typical manufacturer guidance for this hardness).
Estimates for planning, not a quote. Check your appliance manual for exact settings.
Dishwasher setting in Erin
| Brand | Setting for this water |
|---|---|
| Bosch | H05 |
| Miele | 21 °dH |
| AEG / Electrolux | 5 |
| Beko | 6th |
| Hoover | S3 |
| LG | H3 |
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 Erin water hard or soft?
It is very hard: 369 mg/L as CaCO₃ (21.6 gpg, 20.7 °dH). The usual bands are soft < 60, moderately hard 60–120, hard 120–180 and very hard > 180 mg/L.
Is tap water in Erin 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 Erin water?
21.6 gpg, equal to 20.7 °dH, 36.9 °fH or 369 mg/L calcium carbonate.
What dishwasher salt setting should I use in Erin?
For 369 mg/L (20.7 °dH) check your manufacturer's table: maximum level (5–7).
Do I need a water softener in Erin?
Yes, unless you are only passing through: scale damages appliances within a few years.
Source
Source: Ontario Ministry of the Environment, Conservation and Parks, Drinking Water Surveillance Program, Open Government Licence – Ontario (2016). 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