Newfoundland and Labrador

St. John's water hardness

St. John's gets its water from City plants on three lakes. Bay Bulls Big Pond, the largest, supplies the west end and the regional system that also serves Mount Pearl, Paradise, Conception Bay South and Portugal Cove-St. Philip's, and Windsor Lake supplies the east end and downtown. The City does not publish hardness figures, but the provincial government tests tap water in each community every season. In its 2025 results, St. John's tap samples on the Bay Bulls Big Pond supply averaged 26.3 mg/L of hardness over four samples, and Windsor Lake samples 32.8 mg/L over five. Both plants add lime to the water, and both are soft, well under the 60 mg/L line. In St. John's, scale builds slowly, and grease, detergent residue and odours are a bigger worry than limescale.

Data last reviewed October 24, 2026.

St. John's ranks #6 softest of 31 cities in the Canadian Hard Water Report 2026. See the full ranking

At a glance

Bay Bulls Big Pond plant (west end and region)

26 mg/L as CaCO₃ Soft
  • Average
  • Range: 24 to 29 mg/L
  • 4 samples

In other units

US grains per gallon
1.5
Imperial grains per gallon
1.8
German degrees (°dH)
1.5
Millimoles per litre
0.26

Source: Government of Newfoundland and Labrador, Tap water quality for public water supplies, 2025: physical parameters and major ions (seasonal PDFs). Data for: 2025, average of 4 seasonal tap samples (our calculation). Checked October 24, 2026.

Windsor Lake plant (east end and downtown)

33 mg/L as CaCO₃ Soft
  • Average
  • Range: 24 to 39 mg/L
  • 5 samples

In other units

US grains per gallon
1.9
Imperial grains per gallon
2.3
German degrees (°dH)
1.8
Millimoles per litre
0.33

Source: Government of Newfoundland and Labrador, Tap water quality for public water supplies, 2025: physical parameters and major ions (seasonal PDFs). Data for: 2025, average of 5 seasonal tap samples (our calculation). Checked October 24, 2026.

What this means for your appliances

Soft

Scale builds slowly with soft water. Odours, grease and detergent residue are the bigger issue, so clean the dishwasher and the washer about every two weeks.

At this hardness, grease and detergent residue are the bigger issue, so start with the dishwasher.

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Dishwasher hardness setting

Only dishwashers with a built-in water softener have a hardness setting. Here is the setting for this water, worked out from each maker's own table.

BrandBay Bulls Big Pond plantWindsor Lake plant
Bosch and ThermadorCanadian models with a softener. H:00 is off. H:00H:00
GaggenauSame ranges as Bosch. The display shows the °E band. 0-80-8
MieleSet in °dH. Below 5, Miele says no salt is needed. 12
Fisher & PaykelDishDrawer models with a softener. 0 is off. 00

Most North American dishwashers, including Bosch models sold in the United States, have no water softener and no hardness setting. With those, use rinse aid and run a dishwasher cleaner once a month.

Sources: Bosch SHX78CC5UC manual, Thermador DWHD661EFP manual, Gaggenau DF481701 manual, Miele dishwasher manual (Canada), Fisher & Paykel DishDrawer guide

Water softener setting

  • Bay Bulls Big Pond plant2 grains per gallon
  • Windsor Lake plant2 grains per gallon

Softeners take hardness in US grains per gallon: the figure in mg/L divided by 17.12, rounded up.

Coffee makers and kettles

BrandBay Bulls Big Pond plantWindsor Lake plant
Nespresso Essenza PlusHardness level, and cups between descalings Level 0 (4,000 cups)Level 0 (4,000 cups)
Jura E8Hardness setting 1 °dH2 °dH
  • Breville and De'Longhi espresso machines set their hardness level from the test strip in the box, and time the descaling alert from it.
  • Keurig says to descale every 3 to 6 months.
  • Kettles have no setting: descale yours when white scale shows on the element or the base.

Sources: Nespresso Essenza Plus manual, Jura E8 manual, Breville Barista Touch manual, De'Longhi descaling FAQ, Keurig descaling page

Washer

Hard water leaves scale on the heating element and the drum, and more detergent residue behind.

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Guides for hard water

What counts as hard water?

We use the U.S. Geological Survey scale, in mg/L as CaCO₃.

  • Soft 0 to 60 mg/L
  • Moderately hard 61 to 120 mg/L
  • Hard 121 to 180 mg/L
  • Very hard Over 180 mg/L

How to read the units

Utilities usually report hardness in mg/L as calcium carbonate (CaCO₃), which is the same as ppm. Dishwasher and softener manuals often use grains per gallon or German degrees instead. Here is how they convert:

  • 1 US grain per gallon = 17.1 mg/L
  • 1 imperial grain per gallon = 14.25 mg/L
  • 1 °dH = 17.85 mg/L
  • 1 mmol/L = 100.09 mg/L

Questions and answers

Is St. John's water hard?

No. The province's 2025 tap samples averaged 26.3 mg/L on the Bay Bulls Big Pond supply (24 to 29 mg/L) and 32.8 mg/L on Windsor Lake (24 to 39 mg/L). Both are soft water. Water only counts as moderately hard above 60 mg/L.

Which plant supplies my home?

The City says Windsor Lake water goes to the east end and downtown, and Bay Bulls Big Pond water to the west end of St. John's, Mount Pearl, Paradise, Conception Bay South and Portugal Cove-St. Philip's. A third, smaller plant at Petty Harbour Long Pond also serves part of the city; its 2025 tap samples averaged about 51 mg/L, still soft. The City does not publish a map of which plant serves each street.

Do I need to descale appliances in St. John's?

Less often than in harder-water cities. Scale builds slowly with soft water. Grease, detergent residue and odours build up in dishwashers and washers whatever your water, so cleaning the dishwasher and the washer about every two weeks still makes sense.

What hardness setting should my dishwasher use in St. John's?

For dishwashers with a built-in water softener, each maker's table gives: Bay Bulls Big Pond plant (west end and region): Bosch and Thermador H:00, Gaggenau 0-8, Miele 1, Fisher & Paykel 0. Windsor Lake plant (east end and downtown): Bosch and Thermador H:00, Gaggenau 0-8, Miele 2, Fisher & Paykel 0. Most North American dishwashers, including Bosch models sold in the United States, have no water softener and no hardness setting. With those, use rinse aid and run a dishwasher cleaner once a month.

What should I set my water softener to in St. John's?

Bay Bulls Big Pond plant (west end and region): 2 grains per US gallon (rounded up). Windsor Lake plant (east end and downtown): 2 grains per US gallon (rounded up).

What is St. John's's water hardness in grains per gallon?

Bay Bulls Big Pond plant (west end and region): 1.5 grains per US gallon, or 1.8 grains per imperial gallon. Windsor Lake plant (east end and downtown): 1.9 grains per US gallon, or 2.3 grains per imperial gallon.

Where do these numbers come from?

Government of Newfoundland and Labrador, Tap water quality for public water supplies, 2025: physical parameters and major ions (seasonal PDFs). Data for 2025, average of 4 seasonal tap samples (our calculation). We update this page when a new report comes out.

Sources

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Water hardness in St. John's26 to 33 mg/LSoft#6 softest of 31 Canadian citiesCanadian Hard Water Report 2026 by BLITZ Canada
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