Which thresholds trigger the disinfection profile for TTHM and HAA5 as discussed, with Giardia lamblia daily inactivation?

• A. 0.60 mg/L and 0.40 mg/L, Giardia lamblia
• B. 0.64 mg/L and 0.40 mg/L, Giardia lamblia
• C. 0.64 mg/L and 0.25 mg/L, Cryptosporidium
• D. 0.60 mg/L and 0.25 mg/L, Cryptosporidium

Answer: (D)

Disinfection profile triggers are set to step up treatment when disinfection byproduct levels become high enough to threaten consistent pathogen inactivation. The most conservative driver for daily inactivation is Cryptosporidium, because it is more resistant to chlorine than Giardia lamblia, so the profile is designed to guarantee Cryptosporidium inactivation on a daily basis. Therefore, the thresholds that prompt engaging the disinfection profile are TTHM at 0.60 mg/L and HAA5 at 0.25 mg/L. Using Cryptosporidium as the daily inactivation target aligns with the need to address the organism with the highest disinfection resistance, which is why these values are paired with Cryptosporidium rather than Giardia lamblia.