My water supply comes through San Diego's Miramar treatment plant, and here's the data sheet. Here's the relevant part:
Units Avg Range Total Hardness ppm 214 142 - 243 Total Hardness gr/Gal 12.2 8.3 - 14.2
And an excerpt from the footnotes:
Hardness is the sum of polyvalent cations present in the water, which is essentially the sum of magnesium and calcium. These cations are usually naturally occurring.
Okay, now, I'm trying to use this scale under "Determining the Beer Styles That Best Suit Your Water" in Ch. 15.3 of John Palmer's How to Brew:
What is my Effective Hardness? Is it the same as Total Hardness? (In which case, 214ppm seems very high on this scale—Is it possible my water is that hard?) Or, since the footnotes say Total Hardness is a sum, is my best bet to split 214ppm by some rough, sane-looking proportions like 75ppm Mg and 150ppm Ca, thus crossing over on the scale at about 145ppm Effective Hardness?
By the way, my CaCO3 level is 98.2ppm. Not sure this is relevant to hardness though—I imagine it's the non-alkaline Calcium that hardness is measuring.
I do know a store near me where I can get reverse osmosis water for 35 cents a gallon which is basically nothing. I'm more just curious about tap water chemistry, especially for amateur brewing.