Water hardness in Perth
Perth, Ontario tap water is moderately hard, drawn from tay river surface water. Here is what it means at home, and the source.
What this means at home
Some kettle and showerhead scale over time, but most homes get by without a softener.
The 2025 Town of Perth Drinking Water System Annual Report lists a treated-water hardness of 79.6 mg/L as CaCO3 at the water treatment plant discharge.
You likely do not need a softener. A quick test kit confirms it for your own tap.
New to this? Read hard water, explained, including whether it is safe to drink and how to test your tap.
The number, in real terms
At 79.6 mg/L mg/L (4.7 grains per gallon), a four-person Perth household puts only about 1,396 grains of hardness a day through its plumbing (industry sizing convention: about 300 US gallons a day). That is a light enough load that most homes skip the softener and just descale the kettle now and then.
Scale ceiling: every 1,000 litres heated can leave at most 80 grams of scale, because that is the total mineral carried at 79.6 mg/L mg/L. Real kettles and water heaters precipitate a fraction of that, but the ceiling scales with the number: Perth's moderately hard water leaves little behind.
How this is calculated: grains per gallon = mg/L divided by 17.1; daily grain load = gpg x 300 US gallons (the softener trade sizes in US gallons, four-person household); regeneration interval = 32,000 grains divided by the daily load; scale ceiling = mg/L carried per 1,000 L. The input figure is Town of Perth's own published number, checked 2026-07-03. Full method on the methodology page.
Perth water hardness questions
How hard is the water in Perth?
Perth's tap water is moderately hard, about 79.6 mg/L mg/L as calcium carbonate (4.7 grains per gallon), drawn from tay river surface water. Figure from Town of Perth, last checked 2026-07-03.
Do I need a water softener in Perth?
Probably not. Perth water is moderately hard, so most homes get by without one. A simple test kit settles it if you are unsure.
How does Perth compare with nearby towns?
Closest verified figures: Kapuskasing at 80 mg/L, Billings at 73.7 mg/L, Deseronto at 98 mg/L. Perth sits at 79.6 mg/L mg/L, all measured as calcium carbonate.
Source
Source: Town of Perth, last checked 2026-07-03. Hardness varies by neighbourhood, season, and which well or plant serves your street, especially on groundwater systems. These are the municipal published figures as of the verified date, good for planning, not a substitute for a home test or your utility's current report.
Compare nearby verified figures: Kapuskasing (80 mg/L), Billings (73.7 mg/L), Deseronto (98 mg/L). Or see every municipality.