Water Resource Protection | SDWA Regulations: Overview & Implementation

Stage 2 DBPR & LT2ESWT Rules

EPA is proposing the Stage 2 Disinfectants and Disinfection Byproducts Rule (DBPR) to reduce disease incidence associated with the disinfection byproducts that form when public water supply systems add disinfectants. The rule will supplement existing regulations by requiring water systems to meet disinfection byproduct maximum contaminant levels (MCLs) at each monitoring site in the distribution system. The proposal also contains a risk targeting approach to better identify monitoring sites where customers are exposed to high levels of disinfection byproducts. This proposed regulation will reduce DBP exposure and provide more equitable health protection, and will result in lower cancer and reproductive and developmental risks.

The Long Term 2 Enhanced Surface Water Treatment Rule (LT2ESWTR) is proposed to reduce disease incidence associated with Cryptosporidium and other pathogenic organisms in drinking water. The rule will supplement existing regulations by targeting additional cryptosporidium treatment requirements at higher risk systems. This regulation also contains provisions to mitigate risks from uncovered finished water storage facilities and to ensure that systems maintain microbial protection as they take steps to reduce the formation of disinfection by-products.

A summary of key comments made by the Association of State Drinking Water Administrators is provided below. For more information on these rules, go to http://www.epa.gov/safewater/standards.html.

Significant Excursions
Significant excursion requirements should not be regulated until an MCL associated with sub-chronic health effects can be set; therefore, this provision should not be included in the rule. If EPA disagrees, EPA should clearly define significant excursions and not defer to the states to develop individual definitions.

LT2ESWTR Implementation Schedule
States propose modified timelines for both large and small system monitoring schedules as well as staggered implementation for large systems (three groups at: 10-30,000, 30-50,000, >50,000). As proposed, large systems must prepare monitoring plans within three months of promulgation and begin monitoring within six months; the proposal does not indicate if plans will be approved. Extending the implementation schedule and limiting system activity within the first two years after promulgation will give systems more time to choose appropriate sampling locations and prepare for the costs of sampling. It will also give states the necessary time to work with systems; states support a requirement to approve monitoring plans. Staggered sampling may also help to alleviate laboratory capacity concerns.

Stage 2A MCL
States do not support Stage 2A MCLs of 0.120 mg/L (TTHM) and 0.100 mg/L (HAA5) for LRAAs at Stage 1 monitoring locations. Applying different MCLs under Stage 2A may cause more confusion than public health protection, result in data management tracking problems, and increase monitoring and reporting violations. In lieu of Stage 2A, states recommend that water systems comply with the existing Stage 1 D/DBP RAA MCLs until the compliance timeline for Stage 2B MCLs.

Initial Distribution System Evaluation (IDSE)
The concept of performing an IDSE to determine the most appropriate DBP sampling locations is supported. However, conducting an IDSE should not be a regulatory requirement with an associated regulatory deadline. States will assist systems in identifying the most appropriate sample locations and support requirements to approve final sampling plan.

Stage 2 DBPR - Sample Number
The number of required samples should be based on the population served not the number of treatment plants and/or bulk purchase entry points. Minimum sample numbers based on population are proposed by ASDWA with state discretion to require additional monitoring based on system-specific situations.