Which parameter is associated with quaternary ammonium sanitizers?

• A. Minimum temp 75°F
• B. pH 5.0 or less
• C. Water 500 mg/L
• D. Steam temperature 200°F

Answer: (C)

Quaternary ammonium sanitizers are highly sensitive to water quality, especially water hardness. Calcium and magnesium ions in hard water interfere with the sanitizer’s ability to interact with microbial cells, reducing its effectiveness. A common guideline is to keep water hardness at or below about 500 mg/L (as CaCO3). When hardness reaches 500 mg/L or higher, the sanitizer works less effectively, which is why this parameter is the key association. The other factors—a specific minimum temperature, extremely low pH, or steam temperature—do not define quat effectiveness in typical use, since quats operate well across ordinary kitchen temperatures and neutral to mildly basic pH ranges.