Water chemistry

Alkalinity

• alkalinity will effect mash pH
• mash pH will effect: 
• enzyme activity
• yeast acitivity
• beer pH
• tannin extraction
• Residual alkalinity is a measure of the buffering effect of water
• alkalinity is caused by carbonates(CO3--, from the ground), CO2(from the air)
• expressed as ppm CaCO3

Hardness

• hardness is a measure of ions, Ca and Mg ions present in the water
• expressed as CaCO3(Calcium carbonate)
• hardness=50*([Ca]20+[Mg]/12.1) *Mg's influence is half of Ca's
• alkalinity generally bad, hardness reduce alkalinity, hardness is good for brewing
• hard water can be manipulated by the brewer(to achieve desired characteristics we want in our beer, or simply mash pH)

Residual Alkalinity

• RA is the buffering effect of the water/ after Ca&Mg react with phosphates in the malt(to reduce alkalinity)
• if RA is too high, need to adjust the mash(add more hardness or acidify)

Water composition

• potable(safe to drink) water generally suitable for brewing
• except for Chlorine
• activated carbon is used to remove chlorine(&stabilizer)
• especially when you sanitize the brewing water with chlorine
• sulfate(SO4--): 

1. large effect on hop usage(bitterness)
2. more assertive hop character
3. increase bitter linger time
4. too many sulfates bring low quality bitterness=astringent(>300mg/L)
5. concentration should be in the range 0~250mg/L

• Sodium: 

1. can sweeten the malt character at low amounts
2. leads to salty taste in high concentrations
3. concentration should be <50mg/L

• Chlorides: (vs. sulfate)

1. salty taste in high concentration, pasty in very high(>300mg/L)
2. round, sweet quality to malts in modest amounts(bad for hop aroma)
3. concentration should be 0~100mg/L

• Iron: 

1. the less is better, tinny and inky, metallic character
2. concentration when brewing should be Nil(zero content)

• Copper: 

1. metallic taste, indicate pipe corrosion
2. need a small amount for yeast enzyme cofactor 
3. concentration should be <1mg/L

How to understand the water report

• Calcium improves beer clarity, increase yeast flocculation, protect enzyme from heat
• the equation for calculating RA(as CaCO3 in mg/L, like alkalinity): 
• RA=total alkalinity-[Ca]/1.4-[Mg]/1.7  
• Kolbach's rule: link 
• also, what's Kolbach index: link
• mEq/L RA=mEq/L alkalinity-[mEq/L Ca]/3.5-[mEq/L Mg]/7 *mEq/L=milliequivalents per liter 

Adjusting water

• adding sulfates and chlorides should be the first step
• sulfates: chlorides ratio effects taste
• up to 9:1 for really hoppy beer(safer to stick around 4:1)
• 1:2 for malty beer
• calcium sulfate(gypsum salt)
• calcium chloride
• magnesium sulfate(epsom salt)
• magnesium chloride
• now your mash pH reaches 5.3? 
• acid can be used to lower mash pH if the RA is too high
• phosphoric acid(H3PO4)
• citric acid(C6H8O7)
• and lactic acid