I recently moved and plumbed my Lucca M58 into a RO tank in the crawl space under my kitchen. I quickly learned that plain RO water is not really good for espresso, which I should've known already. My shots are suddenly sharp with a lingering astringent taste.

Our tap water is pretty bad here in socal. Tap is about 450ppm and my RO water is about 13ppm.

I tried adding a remineralizing filter between my RO system and kitchen (RO faucet, fridge, espresso) (https://www.amazon.com/gp/product/B00FB ... UTF8&psc=1). Unfortunately when I tested this through my regular RO faucet I got a lot of inconsistency depending on how long the water had been sitting in the filter. For example when I turn it on in the morning my first cup of plain water measures 250ppm, second cup 150ppm, third cup 50ppm and then after that its pretty steady around 18-20ppm.

I've found that the filter doesn't really seem to make the shots taste better and I'm concerned about all the variability that I can't control.

I'm trying to reason through the best way to keep my machine plumbed in so that I can avoid buying/ making water.

I have two ideas but I'm curious what everyone would do in my situation.

Idea 1: Blend back in some tap water (450ppm) into my RO (13ppm) under the house before it comes up to the espresso machine. I could play with the ratio until it tastes good. Probably would need to add at least a sediment filter to make sure I don't send anything too nasty to my espresso machine.

Idea 2: Stack 4-5 of the remineralizing filters together so that it raises the ppm closer to 40-50ppm. In this scenario I'd need to do a "flush" through my sink RO faucet to eliminate the high ppm water that accumulates inside the filters between uses.

I'm sure there's a better option that I'm not considering, thanks in advance for your advice!

Here is a little diagram of my setup. The red dotted line would be "Idea 1" (also would remove remineralization filter)

Do you have a room for a tank to make your own espresso water. I ditched my plumbed in when we moved from CO to AZ. Our RO only serves a tap in the kitchen.

Espresso Cart - Goodbye Plumbed In

I suppose I could put another tank under the house and reroute my espresso water line to that tank rather than the RO tank.

cerone wrote:Unfortunately when I tested this through my regular RO faucet I got a lot of inconsistency depending on how long the water had been sitting in the filter. For example when I turn it on in the morning my first cup of plain water measures 250ppm, second cup 150ppm, third cup 50ppm and then after that its pretty steady around 18-20ppm.

Those numbers are a little discouraging.

A mineral spike in that first draw is a common effect of re-mineralizers. They generally recommend purging some water in the morning before turning the machine on. This seems a little high though, and is perhaps due to over-correction from the Corosex mineral (hard magnesium oxide granules) that they use to help assure a high pH (which is needed to market these to the 'alkaline water' crowd.) Even if you skip the filter purge, I don't think this will give you scale issues. Corosex raises the pH, and adds magnesium bicarbonate to the water. I think you can handle spikes of that without worrying about limescale buildup, and some folks believe that magnesium improves taste.

Getting only 18-20 ppm from an RO that's giving you about 13 ppm (a mineral bump of only 5-7 ppm) does seem low. It depends primarily on the pH and the flow rate thru the filter (lower pH and lower flowrate gives you more mineral.) I wonder if a plain calcite filter might be about as good here. Plain calcite should be less likely to produce that bump of high pH and high TDS initial water.

If you put the remineralization filter between the RO filter and the tank and pull from the tank side, the level will be much more consistent.

Ira

Thanks Ira,
I was thinking of suggesting something like that, but had no experience and figured I'd leave that up to someone who might know.

If moving the accumulator out beyond the remin, one may want to move or add the charcoal finishing filter so that it's between the accumulator and the faucet/espresso line, just to remove any taste/odor that might come from the accumulator.

Also, I realized that I neglected to address Joe's 'Idea 1' -- running a bypass to get hardness/alkalinity up to ideal. That's often done on high end RO systems and a few people on HB have posted about DYI ing that on a home system using a needle valve. It can be a great idea on some water but probably not San Diego, where the chloride ion numbers are up around 100 mg/L and the alkalinity is not much higher than that. Once you blend in decent alkalinity you're also stuck with chloride numbers above what is often recommended for machine health.

And I don't think 'Idea 2' , adding additional remin cartridges, will help much. Once the water goes through the first one the pH is up and the second cartridge will add little or no additional mineral.

Check out my ongoing r/o fine tuning here
Reverse osmosis water system recommendation?