While there are more ways than one for removing chlorine and chloramine from tap water for brewing, an easy and economical way is to add potassium metabisulfite to the brewing water before brewing. Campden tablets are a common form of potassium metabisulfite.
• One Campden tablet = 0.59g weight
• Recommended dosage = 0.59g per 20 gallons, or 0.03g per gallon
• Recommended dosage for 2.5 gallons of water = 0.03g x 2.5gal = 0.075g
• Converting grams to teaspoons
- 1 teaspoon of crushed Campden tablets weighs 5.0g
- Dosage = 0.03g crushed Campden tablet per gallon
- 0.03g per gallon / 5.0g per teaspoon = 0.006 teaspoon per gallon, or 1/166 teaspoon per gallon
• Recommended dosage for 2.5 gallons of water in teaspoons
- 0.006 teaspoon per gallon x 2.5 gallons = 0.015 teaspoon per 2.5 gallons, or 1/70 teaspoon per 2.5
- Converting 1/70 teaspoon to 16ths scale = 16 / 70 = 0.23 of 1/16 teaspoon, or 1/4 of a 1/16 teaspoon.
• Side Effects: Normal dosage for water with 3 mg/L of chlorine produces 3 mg/L additional chloride ions and 8
mg/L additional sulfate ions
• A fudge factor of 20% to 30% is allowable, preferring more rather than less to assure optimum removal of
chlorine and chloramine