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Drinking Water Regulations

(Listed in order by most recent and revised rules first)

The PFAS MCL Rule, published on January 14, 2023 protects public health by setting state MCLs in drinking water for two PFAS – perfluorooctanoic acid (PFOA) and perfluorooctanesulfonic acid (PFOS). PFAS are man-made chemicals which are resistant to heat, water and oil, and persist in the environment and the human body. PFAS are considered emerging contaminants because research is ongoing to better understand the potential impacts to human and animal health. They are currently unregulated in drinking water at the Federal level and are potentially linked to a number of adverse health effects. Proactively addressing PFOA and PFOS contamination in drinking water can reduce the incidence of illness and reduce health care costs. The PFAS MCL Rule and related information can be found on the PFAS Rule webpage.

Lead and Copper Rule
The Lead and Copper Rule was created to protect public health by minimizing lead (Pb) and copper (Cu) levels in drinking water, primarily by reducing water corrosivity. Pb and Cu enter drinking water mainly from corrosion of Pb and Cu containing plumbing materials. The rule establishes an action level (AL) of 0.015 mg/L for lead and 1.3 mg/L for copper based on the 90th percentile level of tap water samples.

Groundwater Rule (GWR)
The Groundwater Rule (GWR) requirements became effective December 1, 2009. The GWR applies to all public water systems that serve groundwater. The rule also applies to any system that combines surface and groundwater if the groundwater is provided to consumers without treatment under the surface water treatment rule. In addition, systems purchasing groundwater from another system are required to comply with certain requirements of the rule.

Stage 2 Disinfectants/Disinfection Byproducts Rule (Stage 2 D/DBP)
The Stage 2 Disinfectants and Disinfection Byproducts Rule is a new federal regulation (NOTE: Stage 1 is a final federal regulation and was published in the Pennsylvania Bulletin on July 21, 2001). The US Environmental Protection Agency created Stage 2 to supplement existing regulations by requiring drinking water suppliers to meet disinfection byproduct maximum contaminant levels at each monitoring site in the distribution system. This rule seeks to better identify monitoring sites where customers are exposed to high levels of disinfection byproducts. This regulation will reduce byproduct exposure, provide more equitable health protection, and result in lower cancer and reproductive and developmental risks.

Long Term 2 Enhanced Surface Water Treatment Rule (LT2 ESWTR)
LT2 ESWTR is a new regulation and was created to reduce diseases associated with Cryptosporidium and other disease-causing microorganisms in drinking water. The Rule supplements the existing regulations by requiring additional Cryptosporidium treatment at higher risk water suppliers. This new regulation also helps to ensure that suppliers maintain protection against microorganisms as they take steps to reduce the formation of disinfection byproducts.

Radionuclide Rule
Regulations for radionuclides in drinking water first became effective in 1976. The revised Radionuclides Rule required implementation for some systems starting in 2005. The rule was revised to improve public health protection by requiring monitoring at all entry points to a drinking water distribution system, to create a new standard for uranium, to change monitoring frequencies, and to create new monitoring requirements for radium-226 and radium-228.

The revised Radionuclides Rule applies to all community water systems (both surface and ground water) and requires them to sample for gross alpha particle activity, radium-226, radium-228, and uranium. Systems that are determined to be vulnerable or to be utilizing waters contaminated by effluents from nuclear facilities, will be notified by Pa. DEP and required to perform additional monitoring.

Bottled, vended, retail, and bulk water hauling systems are also required to provide water that complies with the radionuclide MCLs and to conduct routine compliance monitoring once every four years.

Water suppliers are required to begin radiological monitoring under the revised Radionuclide Rule based on system size with the largest systems (those serving greater than 3,300 people) beginning initial monitoring in January of 2005. Systems serving less then 3,300 people are factored in during later dates.

Long Term 1 Enhanced Surface Water Treatment Rule (LT1 ESWTR)
LT1ESWTR will be the first small system regulation that provides protection against the disease-causing organism Cryptosporidium. In Pennsylvania, the LT1ESWTR is expected to provide additional protection to over 600,000 customers. This rule will apply to about 265 public water systems using surface water or ground water under the direct influence of surface water that each serve less than 10,000 people. Early provisions of this rule take affect in the summer of 2002, but the main provisions are effective in 2005.

Stage 1 Disinfectants/Disinfection Byproducts Rule (Stage 1 D/DBP)
The Stage 1 DBPR is the first of a staged set of rules that will reduce the allowable levels of disinfectants and disinfection byproducts (DBPs) in drinking water. The rule establishes seven new standards and a treatment technique of enhanced coagulation to reduce DBP exposure. The rule is designed to limit capital investments and avoid major shifts in disinfection technologies until additional information is available on the occurrence and health effects of DBPs. The rule applies to all community and nontransient noncommunity water systems that use a chemical disinfectant. Transient systems are affected if they use chlorine dioxide. Large surface water systems serving at least 10,000 people must comply with the rule beginning January 2002. Groundwater systems and small surface water systems must comply by January 2004.

Filter Backwash Recycling Rule (FBBR)
In May 2001, EPA released a rule governing the process of recycling wastewater generated by the backwashing of drinking water filters. The Filter Backwash Recycling Rule (FBRR) is required by the Safe Drinking Water Act as one method of reducing the risks posed to consumers by waterborne disease-causing organisms that may be present in public drinking water supplies. The FBRR applies to all public water systems that:

  • Use surface water or ground water under the direct influence of surface water;
  • Utilize direct or conventional filtration processes;
  • Recycle spent filter backwash water, sludge thickener supernatant, or liquids from dewatering processes.

Interim Enhanced Surface Water Treatment Rule (IESWTR)
The IESWTR applies to filtered water systems using surface water or groundwater under the direct influence of surface water. The rule only applies to systems serving at least 10,000 people. The compliance requirements of the rule are effective January 1, 2002. In Pennsylvania, this rule will provide additional drinking water protection to about 7.3 million people that are served by these large systems. The IESWTR includes requirements related to the performance of filters used in drinking water treatment. The rule revises combined filter effluent turbidity requirements. In addition, certain systems must monitor and record the effluent turbidity of individual filters.

Tools / Electronic Calculators

  • Disinfection Profiling As Required by the Long Term 1 Enhanced Surface Water Treatment Rule
  • Filter Self-Assessment Example Report
  • Disinfection Profiling and Benchmarking Instructions
  • Formula/Calculator Program