Testing tap water for hardness with TF-100


LifeTime Supporter
May 4, 2010
So, I was told that my town delivers "hard water" to my home. This prompted my wife to tell me I needed to install a water softener system. Before I look into that, I decided to test the water for CH using my TF-100 kit. I used the same procedure I use for my pool testing. My results were about 50ppm of calcium hardness.

So my question is......do the reagents used with the TF-100 measure "water hardness" or just " calcium hardness" and are they the same?


TFP Guide
Apr 12, 2016
Tucson, AZ
I may get corrected, but they're mostly the same (I'm assuming here that you're mainly only worried about calcium buildup - salt or some other contaminant won't show up on that test). Someone is feeding you a line. If you really want to make sure, you should be able to get a water quality report from your water company - they'll give you the numbers as they've tested it sometime in the last year or so.

I'd love to only have 50ppm CH in my fill water, it's 225 here!


TFP Expert
LifeTime Supporter
Jun 12, 2009
NW Ohio
Total hardness includes calcium as well as manganese. Both are important when evaluating water softener needs, but for a pool calcium hardness is the only really important factor. So the TF-100 only checks for calcium.

Now, to do this the R-0010 is added to buffer the manganese. So it might be that you can skip that step and get a TH reading, but I have not confirmed this myself. Still, as triptyx mentioned, you should be able to get a water report that will have this number.
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