I finally broke down and had my water tested. I got a W-6 Household Mineral Test from Ward Laboratories, Inc. They have a special order form for home brewers with instructions on how to collect your samples, ship them, and pay for them. They email you your results as a PDF. Here is mine:
The first thing to notice is that there are very few minerals in this water.
This is not very hard water (Total hardness as CaCO₃, 140 ppm). There is some disagreement about definitions for hard and soft water. For instance, Wikipedia uses this scale:
|Very soft:||0-70 ppm|
|Slightly hard:||140-210 ppm|
|Moderately hard:||210-320 ppm|
|Very hard:||>530 ppm|
…while Ward Labs provides this scale in their Guide (p. 150):
|Moderately hard:||75-150 ppm|
|Very hard:||>300 ppm|
In either case, not hard. Somewhere in the Soft-Slightly hard-Moderately hard range. If it were a report card, it would get a “B.”
Since I draw my water out of the same aquifer most everyone else in Happy Valley, Brush Valley, and Penn’s Valley does, you folks ought to seriously consider whether they really need a softener.
All of that is neither here nor there as far as home brewing is concerned. These are the important parts for brewing:
Water by itself does not have much pH buffering capacity and, for a brewer, it is the pH of the mash that is important. The makeup of the grain bill will determine the mash pH. I have included the water pH for completeness because some of the spreadsheets use it. A pH of 7.0 would be perfectly neutral. This water is very slightly alkaline.
Calcium is an important mineral by itself and is necessary for yeast to flocculate. A generally accepted minimum concentration is 50 ppm. There is just enough in my water to allow yeast to flocculate. Lucky me.
Calcium is also one of the knobs that brewers have to control mash pH and there are several ways to adjust it.
Magnesium is also an essential yeast nutrient and co-factor for several enzymes during fermentation and mashing, however, you do not need to get it from your water because malt brings it along to the tune of about 130 ppm. My water has very little, but that is not a problem.
Magnesium is the other knob on mash pH, but it only has half the effect of Calcium (so I like to ignore it).
Bicarbonate is the third control on mash pH, but it really is not much of a control. Most people want to reduce it. To make a light-colored beer you want less than 50 ppm. There are two ways to reduce Bicarbonate: 1) by boiling and cooling to remove “temporary hardness” by precipitating CaCO₃ (calcium carbonate), and 2) by diluting with pure water. A grain bill that will result in an amber beer will counteract up to 150 ppm of Bicarbonate. I do not mind brewing amber beers.
So, what do we have so far?
We have three knobs on mash pH: 1) Bicarbonate, which we cannot do much about, and do not have to so long as we target amber beers, 2) Magnesium, which does not do much nor does it seem to matter, and 3) Calcium, which is necessary and has a large effect. In other words: Brew amber beers and adjust mash pH with Calcium.
There are still three things left on the report: Sulfate, Chloride, and Sodium. You should recognize those last two as Sodium Chloride, or Canning Salt. Table Salt contains Iodine, which is toxic to yeast. Do not use it in your beer. The only reason we consider Sodium here is because it comes with Chloride in the form of Salt. Apart from that it really does not do much for beer. That leaves Chloride and Sulfate. It turns out that Sulfate accentuates hop bitterness, while Chloride enhances maltiness. Just as the BU:GU ratio determines the hop-to-malt balance in a beer, the Chloride to Sulfate ratio does, too.
Apparently a ratio below 0.5 is best suited for a very bitter beer style, 0.5 to 0.77 for a bitter style, 0.77 to 1.3 for a balanced style, 1.3 to 2.0 for malty styles, and above 2.0 for very malty styles.
What does that leave us with?
Brew amber beers. Adjust mash pH with Calcium Sulfate (Gypsum) to have reasonable effect on pH while contributing Sulfate. Balance the Sulfate with Chloride using Canning Salt according to the beer style.
Update: A.J. deLange posted over on The Brewing Network forum that we have read the Ward Lab’s report wrong and that the notation “SO₄-S” means “sulfate as sulfur” which further means that to get the real sulfate amount you have to multiply by 3. I think I’m going to have to redo my calculations. :-/
Perhaps everyone except me already knows this but I just discovered yesterday that Ward Labs reports list sulfate as sulfur (i.e the mg/L number means the milligrams of sulfur in the sulfate – not the mass of the sulfate ions themselves). The popular spreadsheets calculate sulfate “as sulfate” (which makes more sense to me). Before entering your reported sulfate number into one of these spreadsheets convert “as sulfur” to “as sulfate” by multiplying by 3.
Update: I asked about my conclusions on the AHA Forum and got the advice to use Calcium Chloride, instead of Canning Salt, to get my Chloride without adding any Sodium. Since this also bring Calcium, I can use less Gypsum to balance the pH.
Why not get some calcium chloride to go along with your calcium sulfate instead of the sodium chloride?
Update: I was reading The Mad Fermentationist’s post on Homebrew Water Treatment and something he said got me thinking:
If you add a significant amount of pure H₂O it is always a good idea to add some yeast nutrient blend, near the end of the boil, which will replace the trace elements that tap water contains (copper, zinc etc…) which are used by the yeast.
While I am not adding pure H₂O, I do have very pure water to start with. Except for the Calcium, there are almost no minerals, and while the test did not specifically measure copper, zinc, and so on, it did test for the more predominate ones and found very little. If there is not much of the normal minerals, I will bet there is not much of the trace minerals, either. That means it might be good for me to use a Yeast Nutrient, which I stopped doing when I switched from Extract to All Grain because I figured the grains brought everything needed to the party.