Reverse Osmosis Water in Espresso Machines

Water analysis, treatment, and mineral recipes for optimum taste and equipment health.
wcwilson

Postby wcwilson » Feb 17, 2015, 4:49 pm

I was considering an espresso machine where I could plumb my RO water straight in. I've read somewhere that if you don't have enough mineral content then the water sensors don't realize that there is in fact water in the reservoir.

I have a salt water aquarium with a pretty sophisticated RO system and get readings of 000 ppm on my TDS meter. For my drinking water I run the RO water back through a coconut filter which raises the TDS reading to 004 ppm. My question is this reading of mineral content enough to register with the water sensor, or do I need to consider adding additional mineral content back to my water before plumbing it in. I believe the beauty in the RO water is I can avoid descaling, correct?

Thanks,
Wade

emradguy

Postby emradguy » Feb 17, 2015, 5:58 pm

Well, yeah, but there are other factors beside TDS that affect scale buildup (of course, if you have pure RO water there's nothing to scale). What you've read is true about needing some mineral content to activate the autofill mechanism. Personally, I don't know what the minimum threshold is. There are some really good discussion on here, as well as Jim's Insanely Long Water FAQ. If you look at the active thread about Chris' recommending you never descale, you'll see some interesting arguments (some centered about taste of the espresso) for having a higher mineral content (in the 70-150ppm range) in your water than you do...as well as interesting arguments for and for not descaling. In fact, just about everywhere I read about water quality for coffee, I see recommendations for 70-150ppm - solely for flavor purposes. And since we drink it for flavor, and all that goes along with that...what's a little routine maintenance?

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Marshall

Postby Marshall » Feb 17, 2015, 6:51 pm

wcwilson wrote:I have a salt water aquarium with a pretty sophisticated RO system and get readings of 000 ppm on my TDS meter. For my drinking water I run the RO water back through a coconut filter which raises the TDS reading to 004 ppm. My question is this reading of mineral content enough to register with the water sensor, or do I need to consider adding additional mineral content back to my water before plumbing it in. I believe the beauty in the RO water is I can avoid descaling, correct?

While there is considerable debate about the best tradeoff point for flavor vs. minimal descaling, there is almost no serious debate that straight RO water makes terrible coffee.
Marshall
Los Angeles

EspressoForge

Postby EspressoForge » Feb 17, 2015, 7:17 pm

I've a decent RO system that I've started using for my coffee. What I notice is that if you use pure 0 ppm water (distilled or RO), minerals will come from somewhere in an espresso machine, in this case likely your boiler, or scale that has previously built up inside the boiler. Or in the case of HX machines, less so but some taste will come from the inside of the HX. If you do use pure 0 ppm water with no time for minerals to leech into it, I feel extraction is thinner by taste.

I would suggest to add back a bit of tap water, or better, to add something like a piece of bamboo charcoal (you can usually find in places that sell Chinese tea, or online). Gives the water some minerals and a nice taste IMO. I toss a piece into my machine's water reservoir.

Most of this is just anecdotal and based on taste, I don't have a TDS meter, but you can do a function test. Run some water through your machine and taste what comes out, is it good? Metallic? Rancid coffee oil? Will tell you if your water is good, and if your machine is clean.

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Compass Coffee
Sponsor

Postby Compass Coffee » Feb 17, 2015, 7:53 pm

Marshall wrote:While there is considerable debate about the best tradeoff point for flavor vs. minimal descaling, there is almost no serious debate that straight RO water makes terrible coffee.

Flat tasting coffee or auto-fill circuits not registering aren't the only or even least of the problems with distilled or pure RO water. According to water experts pure water is highly a corrosive solvent and will eat through metal.
Mike McGinness, Head Bean (Owner/Roast Master)
http://www.CompassCoffeeRoasting.com

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erics

Postby erics » Feb 17, 2015, 8:00 pm

I was considering an espresso machine where I could plumb my RO water straight in.

Firstly, you should provide a direct link to your RO "system" because all are not configured the same.

Most RO systems are (naturally) equipped with an RO accumulator tank because the steady state output from the system is not sufficient to prevent pump cavitation. Secondly, most RO systems essentially produce distilled water to which some minerals are added back in to produce a tasty beverage (water).

While certainly not for your current needs, these guys have RO "systems" - http://www.freshwatersystems.com/ as do many other internet outlets.
Skål,

Eric S.
http://users.rcn.com/erics/
E-mail: erics at erols dot com

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cannonfodder
Team HB

Postby cannonfodder » Feb 17, 2015, 11:37 pm

Compass Coffee wrote:Flat tasting coffee or auto-fill circuits not registering aren't the only or even least of the problems with distilled or pure RO water. According to water experts pure water is highly a corrosive solvent and will eat through metal.


Look what it did to the wicked witch of the west. 'Help me, I'm melting'
Dave Stephens

wcwilson

Postby wcwilson » Feb 18, 2015, 10:30 am

Thank you all for the information. I think my best course is to just let the city water go through the two micron filters, and maybe the carbon filter (before it goes through the RO unit as well as the deionization canister). That should get out most of the "mud" while still leaving enough minerals to maintain good coffee. It seems as though descaling is a routine that I would just need to have someone do every couple of years if at all.

HoldTheOnions

Postby HoldTheOnions » Feb 18, 2015, 11:26 am

I read before that corrosion comes down to the LSI of the water, which factors several things. I open my boillers periodically and so far I haven't had any corrosion with the stainless steel, but I recently put some copper tubing in my machine, so will see how that holds up. I flush my water each day regardless, but that could be difficult if you have large boilers. Coffee tastes good to me :-)

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Compass Coffee
Sponsor

Postby Compass Coffee » replying to HoldTheOnions » Feb 18, 2015, 1:48 pm

Yes and no. LSI (Langelier Saturation Index) is an equilibrium model derived from the theoretical concept of saturation and provides an indicator of the degree of saturation of water with respect to calcium carbonate. The ability of water to deposit, do nothing (LSI= 0 = equilibrium) or dissolve calcium scale. It seems to be debated in water professional circles how useful LSI is in indirectly estimating water corrosive tendencies.

A small amount of scale formation is a good thing protecting the internals of coffee equipment from corrosion, the actual eating away of metal.
Mike McGinness, Head Bean (Owner/Roast Master)
http://www.CompassCoffeeRoasting.com