Water hardness by town
Most homes in Waterloo Region, Guelph and the surrounding towns get hard to very hard water: 15 to 36 grains per gallon on most municipal systems, and about 78 in Plattsville, which is extremely hard. On our scale, up to 12 grains is mild, 13 to 24 is hard, 25 to 45 is very hard and above 45 is extremely hard. Ontario’s guideline for drinking water is 80 to 100 mg/L, or about 5 to 6 grains.
Kitchener, Waterloo, Cambridge, Wilmot, Woolwich, Wellesley, North Dumfries, Guelph, Rockwood, Fergus, Elora, Milton, Halton Hills and Oxford County
Find your town
Pick your area, then find your town. The big number is grains per gallon, the unit softeners are sized in. The bar shows it against the hardest water on this page, and the darker part shows the range where hardness varies by neighbourhood.
Kitchener
17 to 36 grains per gallon
Hard to very hard
About 291 to 616 mg/L. Varies by neighbourhood
Waterloo
17 to 36 grains per gallon
Hard to very hard
About 291 to 616 mg/L. Varies by neighbourhood
Cambridge
20 to 36 grains per gallon
Hard to very hard
About 342 to 616 mg/L. Varies by neighbourhood
Guelph
21 to 33 grains per gallon
Hard to very hard
360 to 566 mg/L. Varies by well and area
Milton (well water)
19 grains per gallon
Hard
318 mg/L. Depends on your street: part of Milton gets Lake Ontario water
Georgetown (well water)
20 grains per gallon
Hard
342 mg/L. Part of Georgetown has been on lake water since November 2024
Plattsville
78 grains per gallon
Extremely hard
1,327 (average) mg/L. Among the hardest municipal water in Ontario
Woodstock
16 to 30 grains per gallon
Hard to very hard
269 to 515 mg/L. Varies by treatment plant
What your number means
Water hardness is the calcium and magnesium dissolved in your water, measured in grains per gallon. This is the scale we use when we size a softener for homes in this area.
How this compares to official guidance. Ontario’s technical guidance sets an operational guideline of 80 to 100 mg/L (about 5 to 6 grains) to balance scale against corrosion. It describes water over 200 mg/L (about 12 grains) as poor but tolerable, and over 500 mg/L (about 29 grains) as unacceptable for most household uses. The US Geological Survey classes anything over 180 mg/L (about 10.5 grains) as very hard. Hardness is not a health limit, so hard water is safe to drink. Sources: Technical Support Document for Ontario Drinking Water Standards and USGS, Hardness of Water.
The full table
All figures are for municipal water, as published by each town or region. Private wells are different for every property.
How we converted: one grain per US gallon equals 17.1 mg/L. The Region of Waterloo publishes its figures in grains, so its mg/L values here are converted and marked “about”. Halton Region and Centre Wellington publish grain figures using a different conversion, so their own grain numbers look higher; we converted from their mg/L figures so every town is measured the same way.
Your water can be different
Town averages are a starting point. Hardness changes by neighbourhood in Kitchener, Waterloo, Cambridge and Guelph, and every private well is different.
CALL US! 548-255-2662
Water hardness by town, Einwechter Plumbing & Heating, compiled from municipal and regional water reports (October 2026). einwechterplumbing.com/water-hardness-by-townWhat to do about hard water
Questions we get asked
Yes. The Region of Waterloo lists Kitchener and Waterloo at 17 to 36 grains per gallon depending on the neighbourhood. That is hard water in some areas and very hard water in others.
Of the systems on this page, Plattsville has the hardest municipal water, at about 78 grains per gallon (1,327 mg/L) on Oxford County’s 2025 report. Inside the Region of Waterloo, parts of Kitchener, Waterloo and Cambridge reach 32 to 36 grains, and Heidelberg is 32.
Yes. Hardness is not a health limit. Ontario sets an operational guideline of 80 to 100 mg/L, which is about 5 to 6 grains per gallon, to balance scale against corrosion. Water above 200 mg/L is described as poor but tolerable, and above 500 mg/L as unacceptable for most household uses.
It is the unit water softeners are sized in. One grain per US gallon equals 17.1 mg/L of hardness as calcium carbonate. To convert a town report in mg/L, divide by 17.1.
Halton Region supplies part of Milton and part of Georgetown with softer Lake Ontario water (about 7 grains) and the rest with well water (about 19 to 20 grains). Which one you get depends on your street, so check your Halton water bill or call the Region.
Most homes on this page are above 12 grains, in the hard to very hard range, and that is where scale on fixtures, water heaters and appliances becomes hard to ignore. Linwood, and the lake-fed parts of Milton and Georgetown, are mild, and many of those homes do not need one. We will tell you which side of that line your house is on.
A softener does not add salt (sodium chloride) to your water, but it does add a small amount of sodium. Ontario’s technical guidance suggests keeping an unsoftened tap for drinking and cooking if you are on a sodium-restricted diet. Many homes leave the kitchen cold tap unsoftened or add a reverse osmosis tap.
Hard water help
Book a free water assessment by phone. We will tell you what your water needs, and what it costs, before anything starts.
