I am not a chemist, and I don't know what is "the best". But I could share my experience with RO (or maybe this was RO DI system all this time - I honestly did not pay much attention).

I got Home Master Hydroperfection about 5 years ago. I was looking for something that would not only remove the bad stuff, but also remeniralize water on the final stage, because pure H2O is acidic, which is known to cause problems in some individuals with GI issues. I strongly wanted to avoid developing undesirable health conditions over the long period of time.

How is this related to espresso? My Profoitec is still alive without descaling, and so is the electric kettle which is used 10x times a day and still looks almost like new inside. It did not develop any scale or rust.

I shared my experience with Hydroperfection, because this particular model works for me. I am sure there are other great solutions.

makspyat wrote:I'm considering a RO system, and just sticking with my current espresso water practices but using RO instead of distilled. I'm open to suggestions though. If there's a better filtering plan, I'm open to it.

Your water, at a calcium hardness of 40.2 * 2.5 = 100 mg/L as CaCO3, and an alkalinity of 123 mg/L as CaCO3 is a little scale-prone. The good news is that it has nice low chloride ion, so you should be fine with a variety of softening options including the decarbonizing (WAC resin) softeners from Pentair, Mavea, and BWT that have adjustable bypass heads. They would reduce both hardness and alkalinity and acidify the water slightly, and those three factors all tend to reduce scale. I think you could also get by with a conventional softener here, including the LeLit in-tank softener, as long as you take care of the chlorine with a charcoal or carbon filter first. (A pitcher filter like the Brita longlast or a refrigerator filter would do that job.)

makspyat wrote:I'm also curious about RO vs RODI. Is RODI worth it if I decide to go with RO?

When I buy at the dispenser at my grocery store I use the RODI because it's the same price as RO and I think more reliable in case the kiosk RO unit is not well maintained. But as long as your RO unit is producing low mineral water (as tested with a cheap TDS conductivity meter) it should be fine for use in your water recipes.

Your tap water would work very well for doing the same with your coffee water that you now do with beer. For hardness and alkalinity, dilution works as expected, so if you mixed 60% purified (distilled or RO) water with 40% charcoal filtered tap water you would have a calcium hardness of around 40 mg/L, total hardness around 63 mg/L and alkalinity around 49 mg/L - nice water with an ideal alkalinity for espresso machine use. You might see light scale in a hot steam boiler especially if you steam a lot and fail to flush concentrated water from the steam boiler. You could go down to 70% : 30% if you wanted more reliably non-scaling water.

For the beer(all grain), I use tap water(a little harder than yours) and add 1/2 Camden tablet/5 gal. to clear the chlorine and citric acid to bring the Ph down to 5.8+/-. Works well for my IPAs and Stouts.

I'd just run a whole house softener and carbon filter if my chloride was as low as yours is.