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  • TC
    replied
    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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  • slowdown
    replied
    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.

    Leave a comment:


  • slowdown
    replied
    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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  • slowdown
    replied
    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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  • slowdown
    replied
    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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  • Dolcimelo
    replied
    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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  • Dolcimelo
    replied
    Re: RO water bad for coffee machines?

    Thank you very much Mark. I am convinced, and intend to continue unless there is real evidence to convince me otherwise. The one thing I will do, though, is maintain a boiler flushing schedule to avoid increasing concentrations from steaming. This is something I have never done.

    I also have a metallurgist friend who specialises in boiler failures in power stations, and Im sure he will have a sensible opinion. Hes been away recently, or I would have asked him earlier. Ill report what he says.

    Cheers,
    matt

    Leave a comment:


  • A_M
    replied
    Re: RO water bad for coffee machines?

    Originally posted by Bill link=1209725970/60#69 date=1210091604
    Originally posted by AngerManagement link=1209725970/60#67 date=1210085637
    Where did I mention "Pureau"?
    Where did I mention laboratory grade, super high purity RO? Were talking here about coffee machines in a domestic situation, using commonly available water from household type RO units or other similar water commonly available at the supermarket (like Pureau). Not some scientific experiment using the highest grade available. No-one here would be buying water for their coffee machine from a laboratory supply store. You seem to forget the context in which were talking. This is a coffee forum is it not? Not a scientific journal.
    ROFLMFAO A coffee forum it is, however some seem to forget challenge the idea rather than the person... and there is plenty of science being discussed :

    Leave a comment:


  • Sparky
    replied
    Re: RO water bad for coffee machines?

    I am no expert in water chemistry under these environments. However there is a good indication that RO water shouldnt corrosively damage a coffee machine. Copper and its alloys are used for their corrosion resistence in cooling circuits for power stations, and fusion test reactors. De-ionised water is necessary to prevent scale deposits in these situations. I have searched the scientific literature on corrosion properties and find that it does corrode in water. However the corrosion forms a protective black oxide.

    I have downloaded three specific scientific papers on this topic and have come to the conclusion that this is a storm in a tea cup. This villanous super-pure water is a myth. The problem with ultrarure water is keeping it pure. This is only a problem in a lab situation where you need to know the precise conditions under which youre doing something.

    In a coffee machine, a periodic diet of RO water will more than likely help reduce scale deposits in the HX circuit and also the steam boiler if flushed through. So Im happy to continue with business as usual.

    One more thing. Filtered water containing ions wont prevent oxidation of copper, as there is an equilibrium solubility for the copper compounds (which are usually negligible in water) independent of what else is in the water. In fact at higher temperatures, this solubility is increased, further aiding the oxidation process. So boiler corrosion by water will not strongly be affected by the type of water youre using (with certain chemical caveats).

    I dont wish to push this view on to other CSers. Do what sits best with you.

    Cheers,

    Mark.

    BTW, the three papers that I have read are the following:
    Corrosion of brass in ultrapure water, Surface and Interface Analysis, vol 34, p180-184 (2002).
    Corrosion of copper by water, Electrochemical and SolidState Letters vol 10 (11) C64-C67 (2007).
    Erosion-corrosion tests on ITER copper alloys in high temperature water circuit with incident heat flux, Fusion Engineering and Design vol 61-62, p649-657 (2002).

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  • Dolcimelo
    replied
    Re: RO water bad for coffee machines?

    Originally posted by Sparky link=1209725970/60#70 date=1210116088
    However, there are enough ions in solution to allow the level sensor to work.
    Mark,
    Ive seen that said before. So, Im wondering if that also means there are enough ions to prevent corrosion by the process described before, especially as it becomes more concentrated (in my steam-only boiler). So, in fact, maybe we can safely use our RO water and even need to flush to keep the ions down. However, according to the report linked by JavaB, analysis revealed:

    "The levels of dissolved solids are extremely low and equate to distilled, deionised water."

    So, I wonder how there is enough for the sensor. This report was published in 1993, so maybe the products changed. Probably should be re-tested. As for microbiological contamination, well, Im not drinking the stuff, but Im sure its purer than my tap water. The report did say that the particular organism was not pathogenic to humans. I do wonder how hot it gets in cockpits in the tropics, though; probably not quite as bad as my boiler. And thank goodness we dont have to worry about whether the boiler will survive the stresses of an emergency ejection...

    Would love to have a look inside my boiler, but I think thats a bit beyond me.

    Would also love to make a fortune selling tap water with a great logo. But, when I see what most of the world is forced to drink, I feel pretty lucky to have safe water of any kind.

    matt

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  • Sparky
    replied
    Re: RO water bad for coffee machines?


    I agree, Pureau is the water that most people here are using. Another is Aqua Pura, which comes in plastic bottles. Laboratory RO water is made on the spot, not stored.

    As an example, I developed a leak around the element during the use of Pureau (not due to corrosion, but thermal cycling loosening up the fitting). While using Pureau, the leak persisted. As soon as I put in Brita water, the leak sealed itself with scale deposits. So for coffee machine use, Pureau is pure enough that it does inhibit scale build-up.
    However, there are enough ions in solution to allow the level sensor to work.

    Leave a comment:


  • Bill
    replied
    Re: RO water bad for coffee machines?

    Originally posted by AngerManagement link=1209725970/60#67 date=1210085637
    Where did I mention "Pureau"?
    Where did I mention laboratory grade, super high purity RO? Were talking here about coffee machines in a domestic situation, using commonly available water from household type RO units or other similar water commonly available at the supermarket (like Pureau). Not some scientific experiment using the highest grade available. No-one here would be buying water for their coffee machine from a laboratory supply store. You seem to forget the context in which were talking. This is a coffee forum is it not? Not a scientific journal.

    Leave a comment:


  • A_M
    replied
    Re: RO water bad for coffee machines?

    Originally posted by JavaB link=1209725970/60#66 date=1210084287
    There is RO water (real) and there is sudo RO water.... produced by home units and some commercial products.... some of which leave almost as much hardness in their output as tap water - as they arent efficient..... and by the way

    Pureau..... according to http://stinet.dtic.mil/oai/oai?verb=getRecord&metadataPrefix=html&identifier= ADA277068

    Testing done by MATERIALS RESEARCH LABS ASCOT VALE (AUSTRALIA) for suitability as potable water.....

    states that: "The product failed to meet the ADFs stringent microbiological specifications."

    Guess its not real RO after all!!

    And even pure RO doesnt dissolve glass.... it leeches substances out of the glass (ie. very, very slowly will reduce the mass of the glass - and then only very slightly!!!!)

    Well reviewed, and thats the fact of the matter ... There is different water quality where ever you go and RO is not always RO, and unless you have total control, you do not know what had been added.

    In addition, I think you have reaffirmed but clarified a point that some may miss ( the way of text and e-mail) and that is the term leach. To maintain a balanced state it will leach / draw / pull what it needs and depending on how badly it needs it Vs how strongly bonded it it in in other substance, it can take time. Thus for some metals / materials you may not see the difference in the first instance. However if you tested or stress the material it will behave differently. NOTE: There is glass and there is GLASS, just ask a glass blower .....

    Leave a comment:


  • A_M
    replied
    Re: RO water bad for coffee machines?

    Originally posted by Bill link=1209725970/60#62 date=1210081426
    Originally posted by AngerManagement link=1209725970/60#60 date=1210073194
    Try this 2 plastic bottles, rinsed and clean. Fill one bottle 3/4 full with tap Water, then another 3/4 full of RO. Make sure the lids are on tight... I will not tell you the out come... Watch and look with amazement :-)
    Ok, Ill do that with Pureau water, and I bet you $100 that nothing happens.
    Where did I mention "Pureau"?

    Never have in any previous post... If you have a reasonable RO, where the water produced is de mineralised etc, then try my little experiment. If not.. then you are free to try what ever you wish.

    My kids like to drink Nutrient Water.... What a Joke... Have a look at the ingredients " Nature approved de mineralised water" followed by the rest of the additives, fructose, citric acid etc etc including a whole list of minerals and electrolytes calcium and others etc. With a nice marketing logo "You took it from the fridge, we took it from nature" :


    ROFLMAO In other words tap water and some cordial, all be it, able to be reproduced on demand... for $$$$. Worse still its my money :-?

    Some people still believe the world is flat, others believe that Armstrong walked on the moon, others believe that major world events never happened... We see and hear only what we choose too...

    Thus has the discussion "RO WATER bad for Coffee machines? " has lost focus

    Not at all, we all are passionate and get off track at times... That why we post and respect each other

    Nite ALL


    Leave a comment:


  • JavaB
    replied
    Re: RO water bad for coffee machines?

    There is RO water (real) and there is sudo RO water.... produced by home units and some commercial products.... some of which leave almost as much hardness in their output as tap water - as they arent efficient..... and by the way

    Pureau..... according to http://stinet.dtic.mil/oai/oai?verb=getRecord&metadataPrefix=html&identifier= ADA277068

    Testing done by MATERIALS RESEARCH LABS ASCOT VALE (AUSTRALIA) for suitability as potable water.....

    states that: "The product failed to meet the ADFs stringent microbiological specifications."

    Guess its not real RO after all!!

    And even pure RO doesnt dissolve glass.... it leeches substances out of the glass (ie. very, very slowly will reduce the mass of the glass - and then only very slightly!!!!)

    Leave a comment:

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