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Follow up water chemistry questions

Hi All,

Thank you for your help with water chemistry. I am using a combination of reverse osmosis water along with my local well water to create appropriate water electrolyte concentrations for my all grain brews.

The question I have is "what would my RO water alkalinity (CaC03 ppm) be? Would you call this zero because the calcium has been removed by the RO process? Any thoughts?

As a second question, I have been treating my RO water just like distilled water and am assuming it is ion free. Do you think that is a fairly accurate assumption in general? I certainly could have it tested.

Lastly, my water is hard, alkaline, and I am brewing a lightly colored IPA. My brewers friend water analysis calculator recommends phosphoric acid 10% additions to the mash and sparge water to achieve a ph of 5.4. Volumes recommended were 40 cc and 25 cc respectively. That seems like a whole lot of acid to me. Does this sound like it is in the ballpark. I will measure Ph as we go, but just want an opinion from amore experienced brewers.



RO water is not quite the same as distilled, but close enough to zeros across the board.
I can’t answer the phosphoric acid Q. I use lactic acid when Brun water says I should. It’s usually in the 3ml range. But, I would trust what Brewer’s friend tells you.


The phosphoric acid additions could be correct for hard water and a light colored beer. Are you factoring in the fact that you’re diluting this water with RO water in your phosphoric acid addition calculations?

I think you are totally on the right track. For RO water, I would assume zeros for all ions. It’s not exact but it is definitely close to zero.

And yes, you probably need to use that much 10% phosphoric.

So, I have to say, before you do your water adjustments, do check your water pH. How would I know? I used my usual acid correction, and before I add grains, I do check. Went way too low… This isn’t the first time either… So I had enough of this… I checked my plain old water pH… 7… When I had my water tested it was 8.1… So to you peeps that brew with a online water calculator… You best check your pH to see if it has changed… You can’t take for granted its always constant… Sneezles61

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