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  • Reverse Osmosis (RO) Water Quality

    I'm reading a lot of threads about water quality and RO filtration, but what I want to know is what to expect for a water profile for RO water. I assume not all RO filtration systems are created equal, and so I should expect different mineral profiles in RO water from different filtration systems. Is the answer to buy a system, produce water, and have it lab tested? Or is there an industry generic profile for RO treated water? Mostly I want to know so I can figure out how to blend our municipal water to dilute out Chlorides and Sodium, which are both pretty high. I've found this to be a bigger deal in highly hopped and/or lighter beers.

    Cheers,

    Colin Cummings
    Amarillo, TX
    Cheers,

    Colin Cummings
    Amarillo, TX

  • #2
    C'mon, somebody has a good answer.
    Cheers,

    Colin Cummings
    Amarillo, TX

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    • #3
      RO systems will produce pure H20 with no dissolved salts or contaminants in the product. You then have pure water to build up a brewing liquor profile to match what ever type of beer you want to produce. As with any purchase you will get what you pay for. Units rated for flow >500 gallons/day will start at $2500. the under the sink home units are less expensive but the stripping membrane will not be as good. And with a lower flow rate. If you go the RO route, I would advise not to blend municipal back into treated water. Build your water with your own salts and mineral additions.

      Lance
      Rebel Malting Co.
      Silver Peak Rest. Brewery
      Reno, Nevada USA

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      • #4
        Blending

        I have read in a couple of places not to blend back municipal water, and I wonder if I could get an explanation as to why. Is it the difficulty in acheiving a decent water profile through blending? Too complicated? Or adding back in stuff you don't want (chlorides and sodium in my case)? Like others I don't want to waste so much water. I have had good an bad experiences brewing with our municipal water, and the good ones were usually stouts and porters and some ESBs. So I figured, cut it with RO water for pales, blondes and IPAs.

        I'm also curious about this topic because we have discussed doing rainwater catchment for brewing water, and depending on the purity of the rainwater, blending from there since I doubt we could catch enough for our needs (semi-arid climate, after all). So as a second question related to the topic at hand, anyone brewing with rainwater? Is rainwater reliably pure (in a small, relatively low pollution city environment)?
        Cheers,

        Colin Cummings
        Amarillo, TX

        Comment


        • #5
          As has already been mentioned, a good RO system should supply, essentially, H2O with not much else in it!

          Manufacturers should have details of their plant capability and it's always a good idea to ask them if they can provide contacts for existing customers, so you can visit someone who's already using a particular system.

          As regards blending-back, it would be almost impossible to achieve the mineral profile you're looking for by working this way as it's very likely the proportions of the various minerals, salts, etc. in the non-RO water will be correct.

          It's far easier to 'build' the water you want from pure RO by making your own additions - and probably a lot cheaper than having to have either (a) inline blending or (b) mixing tanks.

          I guess collected rainwater could provide a source, but you would need to ensure it was both chemically and microbiologically sound, plus filtration of the particulates that are carried in rain.

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          • #6
            RO water systems should all create pure H2O, but they definitely aren't created equal as far as abilities. System output (how much water it can make), efficiency (how much water it wastes), quality, and cost/frequency of parts that need to be changed out all play a factor. We got our system from US Water Systems, they may not have the stuff you'll need if you are a big time brewery. Charlie at US Water Systems is a great guy to talk to if starting your research.

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            • #7
              Hello,

              OK, so RO systems will not produce 100% pure water; there will always be a little bit of the smaller molecules that make their way through.... but indeed it is very close to "pure".

              Normally you RO for a specific reason - and you have exactly the right reason to do it - reduction of chloride and sodium (I have had this exact issue in the past). You need to try and pick a target level for these so that you design the treatment system appropriately. For me I would target reduction of chloride only down to 50ppm as at levels over that you will may get stress corrosion cracking in some of your brewing equipment (hot liquor pipework, CIP vessels and hot liquor tank mainly).... and then the sodium level will just be what it is.

              Essentially what you will do is do the same pretreatment for all of your liquor (particle filtration, carbon filtration, UV sterilisation) and then split into two streams - one stream to the RO, and another stream that will bypass the RO and blend back, and target a chloride level of <50ppm (40ppm to be safe). At the exit of the RO there will normally be a conductivity meter set up and you will set your bypass up to achieve a specific conductivity. At commissioning you can send some samples off for analysis and get a feel for what the conductivity equates to in terms of ppm chloride, sodium, etc. As RO plants waste a lot of water (recovery rates vary depending on your water supply; can be 50 to 80%, maybe 85% at best) what you want to do is figure out how much you can bypass so that you waste as little water as possible whilst achieving whatever it is you are trying to do in relation to water chemistry.... and then of course simply add gypsum, calcium chloride or whatever else you want to build your water back up.

              Drop me a message if you want any more info as I have experience with a few different systems....

              Cheers,

              Alex

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