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Grains Per Gallon: Water Word Wednesday!!

By August 10, 2016 February 26th, 2021 No Comments

The first thing I learned at college in Winona? All water is not created equal.

My dad has always taken care of my family’s water softener in my southern Minnesota hometown of Owatonna. For 18 years I was spoiled with soft, mineral-free water–not thinking twice about where it came from, or why it was so much better than the water I’d learn to deal with later in life.

Full disclosure: I had never seen a water softener until I began working in this office. Since I started in July I’ve been getting salt science lessons from owner/legend Tom Peterson. Periodically, I’ll update the Peterson Salt Blog with interesting tidbits of my newfound knowledge–stay tuned!


This week I’m incorporating something new into the blog called:

Water Word Wednesday

(because fun alliterations are the best way to understand confusing jargon)

Each week I’ll pick a water softening word or phrase and tack down its definition.
Today’s phrase is…

grains per gallon

(also called: grains, GPG, water hardness level)

This form of measurement is used to describe the amount of calcium carbonate grains dissolved per gallon of water (mineral content); the bigger the GPG number, the harder the water is.

Do you know your water’s grains per gallon? You’ll want to before buying a softener!

Here are some hardness guidelines:


GPG:          Classification:

0-1              Soft

1-3.5           Slightly Hard

3.5-7           Moderately Hard

7-10.5         Hard

10.5>          Very Hard

You can find your city’s GPG by locating its Drinking Water Report online.

Here are a few estimates for Minneapolis suburbs:

Apple Valley= 17
Brooklyn Park= 32
Burnsville= 23
Chaska= 29
Hopkins= 21
Lakeville= 18
Plymouth= 24
Rogers= 22
St. Louis Park= 18

If you’d like further assistance, Peterson Salt & Water Treatment offers free water hardness testing upon request. Call (952) 929-0422 for details!