Large utilities' use of the microbial toolbox for LT2ESWTR compliance

摘要

A survey of public water systems was conducted to determine how they chose to achieve compliance with the Long Term 2 Enhanced Surface Water Treatment Rule (LT2ESWTR). This rule, promulgated in 2006, was intended to increase protection from the risks of Crypto-sporidium contamination by encouraging utilities to adopt a multibarrier approach to drinking water treatment. The rule allowed the use of a number of treatment options, or tools, for compliance. Large treatment facilities were required to demonstrate compliance with the rule by 2012. This survey, funded by AWWA's Water Industry Technical Action Fund, determined which tools large utilities used for compliance and why they chose these particular options. The tools chosen are discussed, the requirements for obtaining credits for Cryptosporidium inactivation or removal are outlined, and the scientific basis for the US Environmental Protection Agency's (USEPA's) decision to grant these credits are reviewed.