So I got back my professional water tests. They were, copied from the marzocco water calculator:

PH 7.8
Alkalinity ppm 53
TDS ppm (75 - 150) 168
Total hardness ppm (90 - 150) 75
Total iron (Fe+2/Fe+3) ppm (0 - 0.02) .01
Total Chloride (Cl-) ppm (0 - 30) 13.5
Free Chlorine (Cl2) ppm (0 - 0.05)
Total Chlorine (Cl2) ppm (0 - 0.10)
Calculated LSI (0.10 - 0.70) .43

Given these numbers, my thought was all I need is a carbon filter, but the LM calculator is saying I need RO plus bypass. I would have thought given my hardness of 75 that I shouldn't be decreasing that at all, and frankly am low on Mg (3.79 mg/l) compared to calcium (22 mg/l).

Am I misunderstanding something, and is there a coffee water/filter consultant out there that the home barista population would recommend?

Perhaps my real question is given a 75 hardness, does the 168 TDS matter? I've read Another_Jim's excellent work several times, but stopped my chemical education after AP chemistry in high school for a reason...

Are you plumbed in or running off the reservoir?

If using the reservoir you could try either mixing in some RO water or even just using a Brita pitcher to filter your tap water, which will remove any chlorine and reduce the hardness some (should be enough to get you under 150 TDS).

BTW, I think the thing I would be most concerned about is the chloride level. Chloride is corrosive to stainless steel. The less the better.

Going to plumb in, so got the water tested professionally to see where I was starting, and to get the data to spec the filter.

I assume carbon takes out the chlorine? I'll definitely put in a carbon and sediment filter

Interestingly on the calculator, when I plug in TDS of 140, it says I need only a sediment filter.

So the question I guess is how much non ca/mg hardness TDS matters?

charlesaf3 wrote:So the question I guess is how much non ca/mg hardness TDS matters?

Check out some of the posts from rpavlis he's a chemist on HB who has posted on this. It's only Ca and Mg that really want to precipitate out of the water and cause scale. Other minerals like Na and K, which may contribute carbonate don't scale. So I would mainly be concerned about the Ca and Mg hardness and not TDS, if that makes sense.

Yeah, that was what I was thinking, but didn't want to rely on my intuitions in this case.