Full disclosure: I’m revisiting a topic I covered seven years ago, back when we filmed with our phones, no microphone, in one continuous take. Even with its terrible sound quality, that video has been viewed more than 190,000 times. I thought it was time to spruce it up.
Hard water is defined by the calcium and magnesium minerals it contains. The higher the mineral content, the “harder” the water.
This test for hard water was something I used to see my dad do in our kitchen. At the time I had no idea what he was doing, other than squirting soap into a drinking glass, which seemed weird. Now I know he was testing to see if our water softener was working.
A true soap can tell you if you have hard water. This is because true soap molecules react with the calcium and magnesium ions in hard water and form a whitish precipitate. This is what we call soap scum on bathroom surfaces. Or, if you make up a batch of my All-Purpose Castile Spray using hard water, you’ll see a cloudy layer that settles to the bottom. This mineral fallout is not toxic but does lessen the cleaning ability of the spray. Not a huge deal, but it can be avoided by using some form of purified water.
The hard water test
Fill a clear glass with tap water.
Squirt in some true soap, such as Dr. Bronner’s Pure-Castile Liquid Soap. (A detergent wash/shower gel/cleanser won’t work here.)
If the soap turns cloudy as it enters the water, you have hard water. If the soap swirls around but stays pretty much clear, you don’t.
That’s the test. It’s not fancy. It’s a simple binary test and does not give you any details such as how hard, but at least you know if you have it or you don’t.
It also makes for a quick little science experiment to do with kids to study the chemistry of water. Or, if you know you have hard water, you can use this test to see if your favorite cleanser is, in fact, a true soap. It all depends on what is the known constant, and what is the variable… (I might have been the mom who made copies of my son’s Algebra homework for my own enjoyment. And we might have raced to see who got done first. What do you do for fun?)
This test isn’t even included as one of the “18-in-1” uses for the Castile Soap. Consider it a bonus.
Remedies if you have hard water
If you have hard water, there are a couple ways you’ll see the effects.
Laundry: Hard water doesn’t rinse the soap off as well.
- Remedy: Add ½ to 1 cup of vinegar to your rinse cycle.
Shiny bathroom surfaces: Hard water leaves soap scum (ring around the tub).
- Remedy: Wipe surfaces dry, and clean once or twice a week with a 50% vinegar spray, or scour the scum away with this fun (yes, I did just use that word) GIY Soft Scrub.
Hair: Hard water can make hair stiff and a little tacky feeling.
- Remedy: Use a slightly acidic rinse after you wash your hair with soap. I use a 50% apple cider vinegar solution, or a couple capfuls of the Dr. Bronner’s Hair Rinse diluted in a cup of water.
Despite these negatives, I don’t see hard water as a wholly bad thing. I have some thoughts brewing about why hard water, though problematic for shiny bathrooms, actually can benefit our skin and overall health. I’ll share all that once I get it all thought through.
For fun, you can check out my original video from my early days on testing for hard water here. We’ve come a long way since then!
This use and many more are in my book, Soap & Soul: A Practical Guide to Minding Your Home, Your Body, and Your Spirit with Dr. Bronner’s Magic Soaps, available now in hardback on DrBronner.com or at your favorite bookseller, and as an eBook and audiobook (read by me!) from wherever you download or listen.