How many logs must a treatment facility maintain for cryptosporidium?

The correct number of logs that a treatment facility must maintain for Cryptosporidium is two logs. This is based on water quality regulations and treatment performance standards aimed at ensuring adequate removal and inactivation of pathogens, which include Cryptosporidium.

Maintaining two logs (or a 99% removal rate) signifies that the treatment process is capable of significantly reducing the concentration of this protozoan parasite, which is particularly resistant to many conventional disinfection methods. This standard is critical because Cryptosporidium has been associated with waterborne outbreaks and can pose significant health risks, especially to vulnerable populations.

In contrast, the alternative choices represent insufficient levels of log removal for Cryptosporidium, which may not guarantee the necessary safety margin for drinking water quality. Therefore, treatment facilities must aim for this robust standard to adequately protect public health.