Using test kit for water hardness

[rlanthony@excite.com]

Can I use my test kit to test water hardness in my house water. I need a new water softener and want to be able to size the softener to the right amount of hardness in my faucet water. Are the test results the same as the ppm for household water? Any thoughts?

Rick

[chem geek]

Rick,

The test for Calcium Hardness found in most pool test kits does not test for Total Hardness which includes Magnesium in addition to Calcium. However, Total Hardness kits are also available. You can also roughly estimate Total Hardness by multiplying Calcium Hardness by 1.4 though that is only for typical mountaing spring sources of water and not mixed sources that have well water -- it's best to get a Total Hardness test kit.

Richard

[rlanthony@excite.com]

Richard ,
Thanks for your reply.
In that I have city water, not well or spring water would the 1.4 calculation still hold true? Would it be good enough to do a rough estimate, then oversize the softener?
Rick

[chem geek]

Perhaps, but if you have a water quality report from your city (check online; they often post them there) then you can probably find both Calcium Hardness and Total Hardness listed separately and usually if only one is listed it's Total Hardness. I have found from my own testing that the numbers in the water quality report match what I measure at the tap.

With something as important as properly sizing the water softener, I would either use the water quality report data or get a real Total Hardness test. The factor of 1.4 is a nice rough estimate, but it could be totally off depending on your specific water situation since it's dependent on the kind of rocks the water has filtered through.

Richard

[rlanthony@excite.com]

Thanks Richard,
I looked in the City web site and found drinking water report. Ca hardness 41.5 ppm, Mg hardness 8.8ppm and Ca/Mg hardness 140. They also gave a Total Hardness as CaCo3 of 168. I am assuming I should use the Ca/Mg Figure for determining the size of the H20 softerner? I promise this is the last time I will bother you about this.
Rick

[chem geek]

I don't know how your water softener is spec'd so I can't answer that question. That is, I don't know if they measure their capacity in calcium carbonate (CaCO3) equivalent. If they do, then 168 ppm (mg/l) would be the number to use, but be careful since the water softener spec might use a different scale such as "grains" for hardness.

Richard