The list below contains most minerals which water can contain and information on each one. Some of these have important effects on the mash, while others are completely neutral.
Effect on Mash and Beer: Acidifies the mash. Releases phosphates. Boosts enzyme action. Develops runoff. Increases the rate of proteolysis. Increases the stability of the finished beer. Increases clarification. Main component of hardness.
Effect on Mash and Beer: Acidifies the mash. Releases phosphates. In large amounts, can cause an unpleasant bitter flavour.
Effect on Mash and Beer: Not particularly important during the mash. Unattractive in excess. When used in moderation sodium provides fullness, particularly to darker beers. Enhances sweetness.
Effect on Mash and Beer: Alike to sodium, but required for yeast nutrition. Not particularly important during the mash.
Effect on Mash and Beer: Provides no effect on the mash when used in moderate amounts. Increases hop bitterness. In low quantities, gives fullness.
Effect on Mash and Beer: Ideal in pale, dry beers, particularly pale ales. Boosts clean hop flavour. Emphasises /sharpens hop bitterness. Lifts colour. Sulfate is usually found in the form of calcium sulfate (CaSO4), or gypsum.
Effect on Mash and Beer: Very alkaline; prevents acidification of the mash. Prevents alpha amylase. Reddens light beers. Accentuates bitterness, but does so in a harsh manner. Does best in lightly hopped and dark beers. Can be removed through boiling, which removes CO2 and transforms bicarbonate into insoluable carbonate.
Effect on Mash and Beer: As an insoluble mineral, when found in this form, carbonate has no effect on the mash or the beer.
Here is a list of ions which can be present in brewing water. Some are vital for yeast nutrition in small quantities but can prove harmful above a certain threshold. Others are contaminants and are always unwelcome. In public water supplies, these are mandated by law to be below harmful levels, but well water may pick up strange amounts of various things. This differs by area. Iron, for instance, can be found in some limestone-derived water, while heavy metals can occasionally be found in mountainous areas.
Notes: Linked to haze formation. Contrary to popular belief, aluminium is very unlikely to leach from cooking vessels into wort during the brewing process.
Notes: Added to public water supplies to remove bacteria, it is usually found at 2 ppm or less. Very toxic towards yeast. Carbon filtration removes chlorine and can be reduced by boiling or allowing water to stand uncovered a couple of days.
Notes: Vital yeast nutrient, but has been show to prevent yeast growth when used in large quantities. Also has an important role in reducing sulphur compounds during fermentation. Can be added during the boil by dropping a couple of pennies in.
Notes: Kills yeast and causes haze formation, and can cause a metallic taste in the finished beer. Can be picked up from iron or steel in equipment. Can be removed in a number of ways, including sand filtration, oxygenation, and chemical treatment.
Notes: Poisonous to both yeast and humans, it can also cause haze. It can get into the water by leaching from brass faucets and solder joints in pipes and equipment. There are specialized drinking-water filters out there which are designed to remove lead and various other heavy metals.
Notes: Similar to lead, this element can be a problem in groundwater.
Notes: Over 10 ppm signifies polluted water. Breaks down into poisonous nitrite in fermentation. Highly undesirable.
Notes: Found only in very polluted waters. Poisonous to microorganisms such as yeast, it is used as a stabilizer in meats.
Notes: Not particularly toxic, but a commanding haze former. Can leak out of solder joints in equipment.
Notes: Needed in very tiny amounts for yeast nutrition, but damaging to yeast in larger amounts.
Cadmium, Mercury, Silver, Arsenic, Beryllium, Nickel
0.001 to 0.1
Notes: Extremely dangerous human toxins and very powerful yeast growth inhibitors. Not usually present in water.