Improving state-level emergency well disinfection strategies in the United States.

After flooding events, well users are encouraged to disinfect their private wells. However, well disinfection strategies are not consistently applied or proven effective. This study examines the science-based evidence that disinfection procedures reduce microbial loading in well water; reviews inclusion of disinfection principles in state-level emergency protocols; and explores research gaps potentially hindering disinfection efficacy. Emergency well disinfection protocols from 34 states were reviewed based on instructions for creating chlorine solutions; circulating chlorine solutions throughout the distribution system; achieving effective CT disinfection (chlorine dose*contact time); and post-disinfection guidance. Many protocols were missing key information about fundamentals of disinfection. Only two protocols instructed well users to verify chlorine residuals and three protocols instructed users to measure water pH. Most protocols recommended that high chlorine doses be introduced into the well, circulated throughout the system, and stagnated for several hours. A CT value estimated to inactivate at least 99.9% (3-log removal) of Cryptosporidium (255 mg-hr/L) was predicted to be achieved by 72.7% of protocols, and estimated CT values ranged from 35 to 16,327 mg-hr/L. Two research gaps identified were determining whether chlorine doses should differ based on well water chemistries and evaluating the appropriate chlorine dose that should be recommended for inactivating pathogens. This effort underscores a need for consistent, evidence-based messaging in emergency well disinfection protocols.

An evaluation of security measures implemented to address physical threats to water infrastructure in the state of Mississippi.

The events of September 11, 2001, increased and intensified domestic preparedness efforts in the United States against terrorism and other threats. The heightened focus on protecting this nation's critical infrastructure included legislation requiring implementation of extensive new security measures to better defend water supply systems against physical, chemical/biological, and cyber attacks. In response, municipal officials have implemented numerous safeguards to reduce the vulnerability of these systems to purposeful intrusions including ongoing vulnerability assessments, extensive personnel training, and highly detailed emergency response and communication plans. This study evaluates fiscal year 2010 annual compliance assessments of public water systems with security measures that were implemented by Mississippi's Department of Health as a response to federal requirements to address these potential terrorist threats to water distribution systems. The results show that 20 percent of the water systems in this state had at least one security violation on their 2010 Capacity Development Assessment, and continued perseverance from local governments is needed to enhance the resiliency and robustness of these systems against physical threats.