… but what to do with it?
I spend a fair amount of time trolling the Northern Brewer forums, and one of the more frequent exchanges goes something like:
Q: OK, I have my water report, now what do I do with it?
A: Read chapter 15 of How to Brew and come back if you have more questions.
Which is technically a good answer, but even I occasionally get tired of being a dick. So, step by step, how to brew… water.
1. Get your water report. This might be available from your municipality, but since they likely average several samples from different locations, their data may not be accurate for your brewery. Your best option is to call Ward Labs, order the W-6 test, and mail in a sample. Either way, the ion concentrations you want to make note of are calcium (Ca2+), magnesium (Mg2+), sodium (Na+), sulfate (SO42-), chloride (Cl-), and either bicarbonate (HCO3-) or the alkalinity as CaCO3. These will be in ppm or mg/L, which for our purposes are equivalent.
2. Use Palmer’s nomograph to find the base-malt pH of your mash. The idea here is that the more alkaline your water is (the higher the carbonates), the more dark roasted grains will be needed to bring it down to the desired mash pH of about 5.6 at room temperature, or 5.2 at mash temperature. For example, my tap water profile is:
Ca2+: 96 ppm
Mg2+: 32 ppm
Na+: 29 ppm
SO42-: 39 ppm
Cl-: 57 ppm
HCO3-: 294 ppm
which is very hard, but not unusual for the Midwest. Plugging those numbers into the nomograph gives a base-malt pH of 5.95, corresponding to a beer color of 18-23 SRM. Essentially, my water can be used to brew only stouts and very dark porters without modification.
3. Adjust the bicarbonate to match the beer. This will require either diluting your water with distilled or reverse osmosis water (to make a lighter beer), or adding carbonates (to make a darker beer). For an example, I’m going to use the amber ale recipe from Good Beer, Easy Beer. This beer has a color of 13 SRM, so I’ll need to dilute my water. Mixing it 50/50 with distilled water more or less halves all the ion concentrations (to 48, 16, 14, 20, 28, and 147 ppm respectively), which brings the base-malt pH down to 5.83. The corresponding SRM range is 11-16, which is pretty much ideal. If you have soft water and need to add carbonates, the sliders on the nomograph page will let you figure out how much chalk (CaCO3) is needed.
4. Check the chloride and sulfate levels. Generally, sulfates highlight the bitterness and flavor of hops while chlorides accentuate malty flavors. 50 ppm is a good starting point, but you may want to go to 150 ppm or more. Unless your goal is extremely malty or bitter, though, I would try to keep the levels of both ions above about 20 ppm, in order to ensure the beer is flavorful and balanced. In the case of this amber ale, I want the hop bitterness to slightly outweigh the malt flavors, so I’m going to target about 100 ppm SO42-, and 50 ppm Cl-. In the case of very bitter beers the sulfates can be even higher, although I personally find that above about 250 ppm the bitterness can be excessively harsh. For this recipe, adding 0.75 grams of epsom salt (MgSO4) and 0.15 grams of calcium chloride (CaCl2) per gallon brings the concentrations to 99 and 48 ppm, respectively.
5. Ensure you have adequate calcium. Calcium is important for yeast health, so you want to keep the level above 50 ppm. Adding chalk, gypsum, or calcium chloride may already have done this; if not then you can add small amounts. Note though that calcium reduces the mash pH; if the effect becomes excessive you may need to add more carbonates, or dilute your base water by less. This is the principal reason that epsom salt (MgSO4), table salt (NaCl), and baking soda (NaHCO3) are sometimes used in brewing: they can increase sulfate, chloride, or bicarbonate, respectively, without adding calcium.
That’s all there is to it. The final water profile for the amber ale is given below. Play around with the nomograph tool a bit, trying to balance all the ions for a few different styles, and I think you’ll find that it becomes second nature pretty quickly. If you have any questions, though, feel free to Contact Me.
Ca2+: 59 ppm
Mg2+: 36 ppm
Na+: 14 ppm
SO42-: 99 ppm
Cl-: 48 ppm
HCO3-: 147 ppm