PWS Guidance

Guidance for Public Drinking Water Systems

Congress enacted the Safe Drinking Water Act(SDWA) in 1974 with the goal of providing safe drinking water to all persons served by a public water systems.  This act provided the EPA authority to establish national standards for contaminants harmful to public health.  Congress amended the SDWA in 1986 and 1996.  Public water systems are required to monitor for a wide range of contaminants.  Some contaminants are considered an acute risk to health such as E. coli, nitrate, and nitrite, meaning they pose a significant health risk to the public from short-term exposure.  Most of the regulated contaminants are a chronic risk to health, which means the health risk is based on long-term exposure (over a 70-year period).  For a complete list of regulated drinking water contaminants, click here.   

Under the SDWA, EPA has promulgated various rules and regulations for more than 90 contaminants, requiring public water systems to have the infrastructure in place and operate in a manner that ensures compliance with these rules.  Below is a listing of the major rules along with the relevant regulations, fact sheets, guidance documents, and report forms:

PWS Forms

PWS Guidance Documents

Public Drinking Water Rules

  • Arsenic Rule

    Effective January 23, 2006, the standard for arsenic in drinking water was lowered to 10 parts per billion (ppb), replacing the old standard of 50 ppb.
  • Consumer Confidence Report Rule

    Effective September 1998, all community water systems must distribute an annual report to the consumers regarding drinking water quality, and system compliance.
  • Disinfectant Residuals, Disinfection Byproducts, and Disinfection Byproduct Precursors:

    • Stage 1 Disinfection Byproduct Rule

    • Stage 2 Disinfection Byproduct Rule

      Effective 2009, this rule focuses on public health protection by limiting exposure to DBPs, specifically total trihalomethanes (TTHM) and five haloacetic acids (HAA5), which can form in water through disinfectants used to control microbial pathogens. This rule will apply to all community water systems and nontransient noncommunity water systems that add a primary or residual disinfectant other than ultraviolet (UV) light or deliver water that has been disinfected by a primary or residual disinfectant other than UV.
  • Ground Water Rule

    Effective December 2009, the rule provides for increased protection against microbial pathogens in public water systems that use ground water sources, in particular, ground water systems that are susceptible to fecal contamination since disease-causing pathogens may be found in fecal contamination.
  • Lead and Copper Rules

    Effective 1992, a regulation to control lead and copper in drinking water was passed. The treatment technique for the rule requires systems to monitor drinking water at customer taps, and to provide corrosion control, as needed.
  • Phase II and V Chemical Rules

    The Chemical Contaminants were regulated in phases, which are collectively referred to as the Chemical Phase Rules. These rules regulate over 65 contaminants in three contaminant groups: Inorganic Contaminants (IOCs), Volatile  Organic Contaminants (VOCs), and Synthetic Organic Contaminants (SOCs). The rules apply to all public water systems (PWS).  PWS type, size, and water source determine which contaminants require monitoring for that system.
  • Public Notification Rule

    Public notification is designed to protect public health by requiring that water systems update their consumers on the drinking water quality and the water system’s compliance.
  • Radionuclides Rule

    Most drinking water sources have very low levels of radioactive contaminants ("radionuclides"), most of which are naturally occurring, although contamination of drinking water sources from human-made nuclear materials can also occur.  Most radioactive contaminants are at levels that are low enough to not be considered a public health concern. At higher levels, long-term exposure to radionuclides in drinking water may cause cancer.   To protect public health, drinking water standards for several types of radioactive contaminants (combined radium 226/228; beta emitters; gross alpha standard; and uranium) were adopted.
  • Surface Water Treatment Rules

    • Interim Enhanced Surface Water Treatment Rule

    • Long Term 1 Enhanced Surface Water Treatment Rule

    • Long Term 2 Enhanced Surface Water Treatment Rule

       The Surface Water Treatment Rules seek to prevent waterborne diseases caused by viruses, Legionella, and Giardia lamblia. These disease-causing microbes are present at varying concentrations in most surface waters. The rule requires that water systems filter and disinfect water from surface water sources to reduce the occurrence of unsafe levels of these microbes.
  • Total Coliform Rule and Revised Total Coliform Rule

    There are a variety of bacteria, parasites, and viruses which can cause health problems when humans ingest them in drinking water. Testing water for each of these would be difficult and expensive. Instead, water quality and public health workers measure for the presence of bacteria in drinking water using coliform bacteria as an indicator. The presence of any coliforms in drinking water suggests that there may be disease-causing agents in the water.
    • Revised Total Coliform Rule (effective April 2016)
  • Unregulated Contaminant Monitoring Rule

    Every 5 years, the EPA uses the Unregulated Contaminant Monitoring (UCM) program to collect data for contaminants suspected to be present in drinking water, but that do not have health-based standards set under the Safe Drinking Water Act (SDWA).  UCMR3 is scheduled to begin in 2013, and end in 2016. 

Contact Info

For more information, contact the Water Supply Program at 410-537-3702 or water.supply@maryland.gov