First, I get bulk RO water from my local grocery store for 49¢ a gallon. I had no idea what was in it (I was using it to dilute bicarbonate in my tap water) so I sent a sample to Ward Labs. I doubt this will help many people because I assume all of these machines are different from each other and even from themselves depending on the filters, etc. While I was at it, I also sent Ward Labs a bottle of Pilsner Urquell. Why? To see if they could tell me what the water ion concentrations were. We always hear that the water is so low on ions. Here we go:
First, my bulk RO water that I get at the grocery store for 49¢ a gallon:
pH: 7.7
Calcium: 10
Magnesium: 4
Sodium: 5
Chloride: 7
Sulfate: <1
Bicarb/HCO3: 50
Total Alkalinity: 41
Total Hardness: 42
All of this seems good except that the bicarb number is higher than I would like for diluting. If I’m diluting 138ppm water with 50ppm water, it’s not much of a bargain so it appears that for that reason alone, I should discontinue using this water and go with distilled which I know is zero across the board.
Next up, a sample of Pilsner Urquell that I hope the fine people at Ward Labs drank when they were done.
pH: 4.5
Calcium: 21
Magnesium: 94
Sodium: 14
Chloride: 192
Sulfate: 69
Bicarb/HCO3: 85
Total Alkalinity: 70
Total Hardness: 444
This sample was an unopened bottle of Pilsner Urquell, btw. I find some of the numbers surprising but what can we learn from this, anything? Check out that magnesium number. Also, I thought it was unusual (and not ordinarily associated with a water report) but this also shows a potassium level of 438ppm and a sulphur level of 69ppm. Are some of these numbers skewed somehow because they come from a sample of BEER and not WATER. Hops, yeast, the presense of alcohol, the grains, etc. Anyone care to comment?
Grain, hops and yeast certainly contain salts, at variable and unknown levels. It might be far more interesting if anyone could test a sample of PU’s actual brewing water!
This is really interesting. I have no scientific input, or anything to bring to the table as far as this thread is concerned, but the subject matter is great. Hopefully we can get some insight from a more experienced brewer because now I need answers.
I had always heard that grains contain trace minerals, etc. and that the beer sample would not necessarily tell us what the brewing water was like. But I hoped that we might learn something. Like… what are the fine people in Plzen adding to their soft water? Why would the soft water matter if they were going to have so many high numbers like chloride and bicarbonate? Does the brewing process (mashing, lautering, boiling with hops, the presense of alcohol and yeast, etc.) make these numbers skewed to the point that we can’t learn anything? I don’t know. I’m going to post this over on homebrewtalk.com where I know that AJ DeLange and Martin Brungard are known to hang out.
That RO machine is out of spec. The TDS is far too high at 52 ppm. That is the reason that I highly recommend anyone using RO water have a TDS meter. They are not too expensive and are a way to quickly tell if the unit is functioning correctly. You want to see a TDS value of less than 20 ppm. My unit is reading about 6 ppm right now.
Malt adds many of those ions identified in the PU report and this result is similar to analyses reported in text: Malting and Brewing Science.
I do note that the ions don’t balance very well in the PU sample, especially if the potassium is that high. I’m assuming that you had not converted that 69 ppm value from an ‘as Sulfur’ value to a sulfate concentration (207 ppm)? When I ignore the K of 438 ppm and make the sulfate adjustment, the report comes somewhat into balance. Balance is achieved with a K of 68 ppm. I don’t have my Malting and Brewing Science text in front of me, so I can’t compare that 438 ppm K result with the text results. I would not be surprised if there are interferences in the lab results due to the high organic content of the beer, so that might affect the ionic content reported.
Very interesting. Thanks for bringing this up.
Martin: Thanks for checking this out. I also posted this on Homebrewtalk because I know that you and AJ hang out there and I was hoping that you guys would see this and tell us what pieces might be useful, if any. The sulfur and potassium numbers were on an Excel doc that Ward sent to me but not on the standard PDF (far shorter document) that I normally see from them. I hadn’t seen potassium or sulphur on an analysis like this before so wasn’t sure what impact it actually had on the experiment. Thanks again.
EDIT: Also, yes the SO4 number is SO4-S (and 69) which means it needs to be multiplied by 3 so 207 is correct. My apologies… I knew that but didn’t make that calc.
