Surface Water Treatment Rule

Public water systems (PWS) treating surface water (SW) or ground water under the direct influence of surface water (GU) are subject to the Surface Water Treatment Rule (SWTR). The purpose of the SWTR is to address the removal of microbial contaminants and to set standards for disinfectant residual levels that must be maintained throughout a PWS distribution system. The current version of this rule is called the Long Term 2 Enhanced Surface Water Treatment Rule (LT2). LT2 includes requirements for addressing Cryptosporidium which is commonly found in surface water. The SWTR requires a PWS treating SW or GU to obtain water quality data through regularly scheduled monitoring. The data includes, but is not limited to, filtration operation and performance, turbidity, and disinfectant residual levels.

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