Comparative Analysis of Water Vulnerability Assessment Methodologies

The Public Health Security and Bioterrorism Response Act of 2002 amended the Safe Drinking Water Act requiring community water systems serving over 3,300 customers to complete water vulnerability assessments (WVAs); however, no specific methodology was provided. Forty-five government and industry agencies associated with water security were identified. Existing WVA methodologies were compared to the EPA’s six-step WVA guidance and an expanded version of the hierarchical holographic modeling (HHM) framework for the hardening of water systems, a technique previously used for assessing vulnerability of infrastructure. Neither the AWWA Water System Security Field Guide, nor the Security Vulnerability Self-Assessment Guide for Small Drinking Water Systems were in complete agreement with the EPA’s WVA guidance. Inclusion of HHM risk scenarios in the assessed methodologies ranged from 64 to 95%. Fifty-nine of the 112 HHM risk scenarios were not included in at least one, and 34 risk scenarios were not included in at least two WVA methods. No method emerged as a “best practice” technique for small and medium sized water systems. Consistent standards for WVA methods are needed.