What are the causes of microbial regrowth in distribution systems and how can it be controlled?
Causes of microbial growth within the distribution system include: • Passage through treatment plant and colonize in system • Reactivation of injured organisms • Contamination from new construction • Contamination from main repair procedures • Contamination during a depressurization event • Backflow (cross-connection) • Back siphonage (cross-connection) • Uncovered storage facilities • Penetration into storage facilities Control measures include: • Remove organisms from source • Provide effective primary disinfection (i.e., no injured organisms to regrow) • Maintain positive pressure • Maintain secondary disinfectant residual • Consider a switch to chloramines • Optimize chloramine treatment • Reduce detention time in storage and distribution systems • Select water with lower temperatures • Reduce pathogen intrusion potential • New main procedures • Sanitary repair procedures • Flushing to keep system clean • Provide corrosion control Question 5: What are the risks, benefits, and other
