The Filter Backwash Recycling Rule is intended to minimize health risks associated with recycling backwash water, particularly with respect to which pathogen?

• A. Giardia
• B. Cryptosporidium
• C. Giardia and Cryptosporidium
• D. All pathogenic organisms

Answer: (B)

The main idea is that backwash water recycled into the treatment process poses a particular health risk from Cryptosporidium. This parasite forms hardy oocysts that are highly resistant to chlorine disinfection and can persist through treatment, making it the biggest concern when backwash water is reused. The Filter Backwash Recycling Rule targets this risk by requiring measures to inactivate or remove Cryptosporidium before backwash water is reintegrated, protecting the treated drinking water supply. Giardia is also a protozoan pathogen, but it is generally more susceptible to disinfection, so it’s not the primary focus here. Saying all pathogenic organisms is too broad because the rule concentrates on the most resistant and relevant threat in backwash scenarios, which is Cryptosporidium.