Would scale be an issue with RO filter water with 5 stages of carbon filters? I even have the house on a carbon filter as well.

A reverse osmosis filter filter and carbon filters? Seems excessive. But to answer your question, scale should not be an issue. I would be more concerned about the lack of minerals impacting your espresso's taste than the scale buildup. David Lewis recommends reverse osmosis and calcite filter (e.g., OmniPure K5648 available here).

Yes RO does a great job with scale but like Dan points out
completely lack of minerals means
completely lack of voltage reading which can affect the autofill system in some less sensitive boards
and also the taste gets affected as well

Not mentioning what machine you have makes it difficult to say exactly. RO water is reportedly hard on copper pipes as it can leach the pipes eventually causing a failure. I have read warnings to folks installing RO systems that copper should not be used to plumb an ice maker for that reason (any of our resident scientists have further info on this?).

As Stefano stated, if your machine has autofill for the boiler then RO water will (can) cause overfilling of the boiler and can lead to pump failure as the pump will not shut off.

Then there is the issue of taste. I suggest that you read Jim Schulman's "Insanely Long Water FAQ" for more information on that.

Last year I added a calcite filter after the reverse osmosis system and it made a discernible difference in the taste of the espresso. Although the drinking water itself had always been delicious and clean, the espresso it made was flat. Adding the calcite filter seemed to my not terribly sophisticated taste mechanisms to help.

In fact, I just ordered a new one....from here
http://www.espwaterproducts.com/omnipure/k-series.htm

Susan

HB wrote:A reverse osmosis filter filter and carbon filters? Seems excessive.

The RO units I work with need carbons for chlorine removal. Chlorine will degrade the membrane and eventually ruin it.

Cheers,
Troy

SJM wrote:Last year I added a calcite filter after the reverse osmosis system and it made a discernible difference in the taste of the espresso. Although the drinking water itself had always been delicious and clean, the espresso it made was flat. Adding the calcite filter seemed to my not terribly sophisticated taste mechanisms to help.

In fact, I just ordered a new one....from here
http://www.espwaterproducts.com/omnipure/k-series.htm

Susan

Hi Susan, (and everyone else)

Excellent! Thanks for the tip!

Jeff

According to this website it states it can be corrosive to copper pipes.

Go to the bottom of this page.
http://www.ag.unr.edu/walker/WebPublications/FS-05-10CSREES.pdf

I will use a calcite filter as per Susan if I plumb one in. I do not have RO going through anything other than plastic and stainless now. I am glad every one brought this to my attention since I just read an ad for a machine that had been feed RO water directly.

Alright, I will admit that I currently only use water treated by RO to avoid descaling. I started using RO water when I acquired my first machine earlier last year, it's worked fine for me so far. I'm willing to try different types of water treatment options, but RO is just so darn easy, it's hard to make that change.

About 2 months ago I purchased a used Rancilio Silvia from a coworker, I tore into it and found the boiler full of scale. I used a product to remove scale from my local espresso dealer, but found that it removed most, but not all of the buildup. I'm in the dark when it comes to descaling espresso machines, I'm really focused on pulling good shots on a regular basis. I'm not trying to brag here, but I think I'm pretty consistent with my shots, now it's time to learn about descaling so I can experience the mineral jumbo that everybody's talking about.

I recently tried Illy's "Espresso Dark Roast," I found it kinda bland in comparison to the Peace Coffee (Fair Trade Organic) that's locally roasted. I could see that there would be a difference using spring water for the Illy stuff, but the Peace Coffee probably has my buds dancing in comparison to Starbucks or other local coffee shops coffee.

So... the big question is, which is going to cause more damage; RO treated water over time to brass and copper or spring water with mineral buildup? I think the first is something more to worry about, but the definitive question is... How long will it take to cause any noticeable damage?