dale_cooper wrote:However, is all distilled water or RO water the same? My grocery sells RO water where you can fill your own jug for 39cents.
They aren't quite the same. Distilled water is generally very pure. ZeroWater is also relatively pure; it's usually 1-2 ppm, and at 6 ppm you know to change the filter. RO varies depending on the efficiency of the unit and the mineral content of the incoming water. I believe the RO stations at the grocery store run in the 5 - 50 ppm range. (I understand some of them have a TDS monitor on the output and shut the unit down if it goes as high as 50ppm.) You can always check your grocery store water with a cheap TDS meter - that's one thing they are very good for.
For me, I would use RO, distilled, or ZeroWater without worrying about the 30 ppm or so difference - is pretty negligible if I'm spiking the water with minerals. And there is little to worry about with respect to chloride, sulfate, silica, etc - even if the incoming water is high in those minerals they will be reduced to insignificant levels after RO treatment.
AgileMJOLNIR wrote:Since I'll be running off the LMLM's reservoir I see that on La Marzoccos website they recommend Crystal geyser for those of us like me on the West Coast and then Acqua Panna.
A lot of earlier comments also mentioned Crystal Geyser. Take care with that as the Crystal Geyser Alpine Spring Water may come from any one of six very different sources. Even on the west coast you have the Weed/Mt Shasta (soft) and the Olancha Peak (not soft). I think either would work fine, although the Weed source is way below the LM recommendation for hardness. I think that's OK, even preferable if you don't ever want to descale your machine. (Eric Svendson posted a nice summary table of CG Alpine Spring waters here: Blonding too fast. Profitec 700.
Acqua Panna is a neighbor of La Marzocco near Florence. It's a little high in hardness and alkalinity, at the upper limit of LM recommendation for hardness and slightly above their upper limit for alkalinity. (And LM recommendations are higher than most machine manufacturers.) If you use that just keep an eye out for scale.
(I posted my opinions on CG - Olancha and Aqcua Panna a while back - see Best bottled water for espresso machine
Also, Greg (8899) mentioned Fiji bottled water in the post above. That's an interesting one because it does come from volcanic rock and has over 90 mg/L silica content. That level would make me rule it out for routine use in an espresso machine. But it may be interesting to taste test in a pourover or cupping as an example of a moderately hard, high alkalinity water.
Fiji numbers available at http://www.fijiwater.com/faqs.html 18 mg/L Na⁺
4.9 mg/L K⁺
18 mg/L Ca²⁺
14 mg/L Mg²⁺
9.2 mg/L Cl⁻
153 mg/L HCO⁻
92 mg/L SiO₂
0.23 mg/L F⁻
224 mg/L TDS
45 mg/L calcium hardness (CaCO3 equiv)
103 mg/L total hardness (CaCO3 equiv)
125 mg/L alkalinity (CaCO3 equiv)