Water chemistry without a chem degree
Bru'n Water spreadsheet plus 2 brewing salts fixes 90% of water issues. The honest setup that doesn't require chemistry textbooks or RO systems.
Brewing water chemistry intimidates new brewers, partially because the books make it sound like an organic chemistry exam. It isn't. For 90% of home brewers, getting water right means three things: getting rid of the chlorine, getting the pH in the right range, and adjusting the mineral content for the beer style.
Here's the honest framework.
Step 1: deal with chlorine
Almost all US municipal water has chloramine (chlorine bonded with ammonia for stability). Chloramine survives boiling and ruins beer — it produces medicinal off-flavors called chlorophenols that you'll taste at parts per billion.
The fix is one Campden tablet (potassium metabisulfite) per 20 gallons of water. Crush, dissolve, stir. Reaction is instantaneous. Half a tablet per 5-gallon batch is plenty. Cost: $4 for 50 tablets, which is a 5-year supply for the average home brewer.
Skip this step at your peril. Untreated tap water is the most common cause of "what's wrong with my beer?"
Step 2: know your starting water
Get a water report from your municipality (free, usually online). What you care about for brewing:
| Element | Typical range | Brewing range |
|---|---|---|
| Calcium (Ca) | 10-150 ppm | 50-150 for ales |
| Magnesium (Mg) | 5-30 ppm | 10-30 for ales |
| Sodium (Na) | 5-100 ppm | under 100 |
| Chloride (Cl) | 10-100 ppm | see style |
| Sulfate (SO4) | 10-300 ppm | see style |
| Bicarbonate (HCO3) | 10-300 ppm | see style |
If your tap water has bicarbonate over 200 ppm or chloride/sulfate are very far out of range for the beer styles you want, you may need partial RO (reverse osmosis) dilution. For most home brewers in soft- to medium-water areas, tap water with adjustments is fine.
Step 3: two brewing salts cover most styles
You need exactly two minerals to adjust most beer water:
- Calcium chloride (CaCl2). Adds calcium and chloride. Chloride enhances malt sweetness and body. Use for stouts, porters, malty beers.
- Gypsum (CaSO4). Adds calcium and sulfate. Sulfate enhances hop bitterness and dryness. Use for IPAs, pilsners, hoppy beers.
For a 5-gallon batch, typical additions:
| Beer style | CaCl2 | Gypsum |
|---|---|---|
| American IPA | 2g | 6g |
| British bitter | 2g | 4g |
| Stout / Porter | 4g | 2g |
| German pilsner | 2g | 3g |
| Wheat beer | 3g | 2g |
These are starting points, not optima. Adjust based on results and the spreadsheet.
Step 4: the spreadsheet
Bru'n Water (free, made by Martin Brungard) is the only water chemistry tool worth using. It takes your starting water report and target style, calculates the salt additions, and tells you the predicted mash pH.
The interface is intimidating. Spend an hour with it once and you'll never have to think about water chemistry again for that water source. Updates are usually a 30-second adjustment when you change beer style.
The free version handles 95% of what home brewers need. The paid "Supporter" version adds a few features that are nice but not necessary.
What about RO water?
Reverse osmosis water has near-zero minerals and a neutral pH. Many advanced brewers use RO water and build the profile from scratch with brewing salts.
The honest answer: RO is only necessary if your tap water has problems you can't fix by adjustment. Examples: very high alkalinity (over 300 ppm), high sodium (over 150 ppm), or weird metallic flavors that follow the water rather than the beer. For most US brewers, RO is unnecessary complexity.
If you want the brewing convenience without buying an RO system at home, distilled water from the grocery store works perfectly. $1.50 a gallon. Building from distilled water gives you absolute control with no investment.
Mash pH: the one number that matters
Mash pH between 5.2 and 5.6 is where good beer happens. Lower than 5.2 produces thin, acidic flavors. Higher than 5.6 produces astringent, harsh flavors and poor enzymatic conversion.
Bru'n Water predicts mash pH to within 0.1. A $40 pH meter (cheap is fine for this) lets you measure during the mash. If you're consistently outside 5.2-5.6, adjust water salts or add acid malt (1-2% of the grist) to lower pH, or add baking soda or pickling lime to raise it.
