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  • #76
    Re: RO water bad for coffee machines?

    Hi cremakid,
    I had a chance to talk to him last night, and his professional opinion is that there is no chance of corrosion in this context. He bases this on the use of marine brass (also called naval brass) in power stations and other industrial plants. As far as I know, all brass coffee machine boilers use marine brass. This has additives (I think arsenic or tin) which prevent de-zincification. They are not toxic when added to the alloy in this way. Any brass components in plants like power stations can only be used with de-ionized water to avoid scale, which otherwise can cause catastrophic failures, so marine brass is always used.

    Yes, this also includes distilled water, if it has no minerals added back in, of course. A regular flushing schedule must be maintained for closed boiler systems like a steam boiler. I believe I have described what he said accurately, but any mistakes will be mine, not his.

    In the case of your single boiler, its not mineral concentrations but scale that you have to watch. Flushing will not protect you from this. If the water is sufficiently hard and alkaline, then scale will precipitate out at boiler temperature until the hardness falls to a level where the Langelier Index is 0. Therefore, you must soften your water or descale regularly. Have a look at the "Insanely Long water FAQ" referred to earlier, here: http://www.big-rick.com/coffee/waterfaq.html

    matt

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    • #77
      Re: RO water bad for coffee machines?

      Phew, this thread has been an insanely long read.

      I use RO water in my machine and got wind that it might not be good for you. Started worrying about Cu ions in my coffee and all that.

      I think getting to the end of this thread though, it appears to be a bit of a storm in a teacup - at least for my home RO system, which delivers water with around 60 - 100 mg/L of dissolved solids.

      BTW, I tested the pH of the water options I have here in Perth - tapwater 7.6, RO 7.3, steam from the boiler 7.3 (not sure if my pH test meter is calibrated - and I dont know the pH of Perth water and I cant find it on the website).

      Just to be sure though, I am going to install a remineraliser unit downstream of the RO!

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      • #78
        Re: RO water bad for coffee machines?

        The remineralising cartridge arrived today, as well as a Total Dissolved Solids (TDS) meter.

        I got the following readings:

        Perth tap RO water RO water + remineralise

        TDS 385 17 30
        pH 7.7 6.9 8.9

        As noted above, the pH meter is not calibrated, so only the pH relativities are (presumably) reliable. I must say the high swing reading on the pH is surprising to me. I cant figure this - not being a chemist.

        It also appears as if the alkalinity and hardness (assuming these are the same at 30 mg/L) are still a little low. Note, if correct, this TDS reading should suggest a pH of around 6.7 according to Shulmans table in Section 4 of his Insanely long water note linked above.

        All in all, Im confused. Does anyone understand the link between TDS and hardness and alkalinity and pH?

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        • #79
          Re: RO water bad for coffee machines?

          Whoops, the above RO water + remineralise was with the remineralising cartridge as the last element in the system. The water was very cloudy - clearly the presence of dust from the cartridge in the water - which must have been bumping up the pH somehow.

          I have now put the remineralise cartridge before the post filter - so that the cloudiness is filtered out. I get the following readings:

          RO + remineralise + post filter
          TDS 46
          ph 7.8

          That is much better - assuming tap water has close to neutral pH of 7 - this water is only slightly more alkaline. Based on the Schulman table, a TDS of 46 implies a pH of very close to 7.

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          • #80
            Re: RO water bad for coffee machines?

            Interesting to note that Schulman rates Ion Exchange (water softener) water as inferior to (pre-) boiled water, but about the same as RO with a proportion of pre-RO water added back in to bring it back up to a TDS of around 50.

            Maybe the cheapest and best solution to ideal coffee water is just to boil water in the kettle before adding it to the machine.

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            • #81
              Re: RO water bad for coffee machines?

              Originally posted by 5946455D4E455D442A0 link=1209725970/79#79 date=1247026732
              Interesting to note that Schulman rates Ion Exchange (water softener) water as inferior to (pre-) boiled water, but about the same as RO with a proportion of pre-RO water added back in to bring it back up to a TDS of around 50.

              Maybe the cheapest and best solution to ideal coffee water is just to boil water in the kettle before adding it to the machine.
              Hmm...You boil, you lose oxygen...

              I think ion exchange has improved dramatically in the last few years- so long as you buy the right gear. I have had awful, rubbery tasting ion exchange and gorgeous sweet stuff as well.

              Mine is from Bombora and I reckon Bernard and his crew are very much on the money...

              2mcm

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