U.S. Tightens Drinking Water Standards

On December 3, 1998, President Clinton announced new public health standards for drinking water, the first such standards to be issued by the Environmental Protection Agency (EPA) under the 1996 Amendments to the Safe Drinking Water Act (1996 Amendments). The decision that the President should announce these new rules, rather than EPA Administrator Carol Browner, results in part from the singular importance Americans attach to safe drinking water, in part from public works' expenditures on the local level for drinking water infrastructure, and in part from the President's desire in the extraordinary political climate now prevailing in the nation's capital to reach out to the electorate on an issue known to attract intense public concern.

The new regulations are designed to balance the twin goals of protecting drinking water from microbes and viruses and minimizing the public's exposure to disinfection by-products. The regulations, titled the Interim Enhanced Surface Water Treatment Rule and the Stage 1 Disinfectants and Disinfection By-products Rule, are the first of a series of ground and surface water antimicrobial and disinfection by-products rules to be promulgated. Additional regulations are scheduled to be issued in 2000 and 2002.

After Cryptosporidium outbreaks in the United States in the early 1990's, Congress reacted quickly to public concern that the Safe Drinking Water Act did not adequately protect public health. States and local municipalities also informed Congress that they lacked the necessary resources to fully comply with the Safe Drinking Water Act. The 1996 Amendments thus were enacted to enhance source water and ground water protections, develop drinking water standards using a scientific risk-based approach, and provide funds to some public water systems, especially small systems, for infrastructure improvements to enable them to comply with the requirements of the Safe Drinking Water Act.

The 1996 Amendments may also have created, perhaps unintentionally, a basis for even greater public anxiety over the quality and potential health risks of its drinking water. Under the 1996 Amendments, states began last year to compile information from individual systems so consumers could assess the overall quality of drinking water in their states. Beginning this year, these systems must prepare and distribute annual consumer confidence reports that will include information about the source of the systems' drinking water, monitoring results from that year, and information about health concerns generated by violations of the Safe Drinking Water Act for that year.

These regulations are certain to increase public water systems' construction, operation, maintenance, treatment, monitoring, and reporting costs. While these costs can eventually be passed on to the consumer, the system must provide the initial funding to implement the new requirements. The Drinking Water State Revolving Fund program, created under the 1996 Amendments, assists public water systems (both publicly and privately owned) in financing infrastructure and other costs to achieve or maintain compliance with the Safe Drinking Water Act requirements. Individual states have developed, or are in the process of developing, criteria for determining a water systems' eligibility for funds.

The Interim Enhanced Surface Water Treatment Rule

The Interim Enhanced Surface Water Treatment Rule (IESWTR) amends the 1989 Surface Water Treatment Rule to strengthen microbial protection, including specific provisions to address Cryptosporidium. It applies to all public water systems using surface water, or ground water under the direct influence of surface water, that serve 10,000 or more people. Surface water is defined under the SDWA as "all water which is open to the atmosphere and subject to surface runoff."

Like the Surface Water Treatment Rule that established Maximum Contaminant Level Goals (MCLG) and treatment requirements for viruses, bacteria, and Giardia lamblia, the IESWTR sets the new MCLG for Cryptosporidium at zero. MCLGs are non-enforceable public health goals and represent the maximum level of a contaminant in drinking water at which no known or anticipated adverse health effects occur.

The new rule also sets performance standards for the removal of Cryptosporidium from filtered and unfiltered water systems. For unfiltered systems, the rule requires a public water system to include as part of its watershed control program measures to minimize the potential for source water contamination by Cryptosporidium. This program must include a characterization of watershed hydrology, land ownership, and activities that may affect source water quality. For filtered systems, existing combined filter effluent turbidity performance standards are strengthened. The rule also requires continuous individual filter turbidity monitoring. New finished water reservoirs are also required to have covers.

Under IESWTR, water systems must also generate disinfection profiles and establish disinfectant benchmarks. These profiles and benchmarks are to ensure there will be no reduction in protection from microbes as a result of modifying disinfection practices in order to meet limits set for the disinfection by-products by the Stage 1 Disinfectant and Disinfection By-products Rule (discussed below).

Finally, the states are required to conduct sanitary surveys and prepare sanitary survey reports for all surface water systems, regardless of size and regardless whether the systems use filtration. The states must then review these results to determine whether the existing monitoring and treatment practices for the system are adequate, and if not, implement appropriate rules or other authority to address the deficiencies identified in the surveys.

States have two years to adopt and implement the rule. Public water systems regulated by the rule have three years to comply with the new requirements. Beginning in March 1999, however, public water systems must begin taking water samples in order to generate disinfection profiles and benchmarks.

The Stage 1 Disinfectant and Disinfection By-products Rule

The Stage 1 Disinfectant and Disinfection By-products Rule (DDBR) is intended to minimize exposure to disinfection by-products that form from the reaction of disinfectants with naturally occurring materials in the water. Based on toxicological studies that have shown several disinfection by-products (e.g., bromodichloromethane, bromoform, chloroform, dichloroacetic acid, and bromate) to be carcinogenic in laboratory animals and other disinfection by-products (e.g., chlorite and certain haloacetic acids) to cause adverse reproductive or developmental effects, EPA concluded that disinfection by-products present a potential public health risk that must be addressed. Several epidemiological studies have also suggested a weak association between certain cancers or reproductive and developmental effects and exposure to chlorinated surface water.

The DDBR applies to all community and nontransient noncommunity water systems that add disinfectants to their water during any part of the treatment process (including the addition of a residual disinfectant) and to any transient noncommunity water systems that use chlorine dioxide as a disinfectant or oxidant.¹ The DDBR creates maximum residual disinfectant level goals (MRDLGs) and maximum residual disinfectant levels (MRDLs) for three chemical disinfectants; chlorine, chloramine, and chlorine dioxide. The EPA uses MRDLGs and MRDLs, instead of MCLGs and Maximum Contaminant Limits (MCLs), to reflect the fact that these substances have beneficial disinfection properties. Like MCLGs, MRDLGs are non-enforceable public health goals that represent the maximum level of a contaminant in drinking water at which no known or anticipated adverse health effects occur. The MRDLs are analogous to MCLs which are enforceable legal standards and represent the maximum permissible level of a contaminant in water which is delivered to any user of a public water system. However, unlike the MCLs, the MRDLs recognize the benefit of adding a disinfectant to water. For the three regulated disinfectants, EPA set identical MRDLGs and MDRLs.² The DDBR also establishes MCLGs and MCLs for the disinfectant by-products -- trihalomines, haloacetic acids, chlorite, and bromate. The DDBR replaces the existing MCL levels established in 1979 for trihalomines.

One of the DDBR's goals is to reduce the reaction of naturally occurring organic materials with disinfectants that create disinfectant by-products. The DDBR therefore requires systems which use conventional filtration methods to remove specified percentages of organic materials. Two treatment techniques, enhanced coagulation or enhanced softening, are to be utilized for this removal.

Surface water systems that serve populations of 10,000 or more are required to meet the DDBR requirements within three years. Ground water systems and surface water systems that serve populations under 10,000 must come into compliance within five years.

Future Rule Makings

EPA promulgated an Information Collection Rule (ICR) in 1996 to establish monitoring and data reporting requirements for public water systems. This rule provides EPA with information about the amount of disinfectant by-products and disease-causing microorganisms in public water systems, and about how public water systems currently control such contaminants. Only surface water systems that serve populations over 100,000 and ground water systems that serve at least 50,000 people must monitor and report under this rule. Since implementation of the ICR took longer than expected, the results were not ready to be used in preparing this first set of rules. EPA expects information from the ICR to be available by the end of 1999 and intends to refine the IESWTR and DDBR based on those results. While the ICR will greatly increase the current knowledge about the extent and treatment of disinfectant by-products and microbes, there will continue to be much scientific uncertainty about both the health risks associated with disinfectant by-products and the best way to treat them³.

Despite this uncertainty, EPA must comply with the deadlines set in the 1996 Amendments to the Safe Drinking Water Act. EPA is scheduled to promulgate a final rule for long term enhanced surface water treatment that will apply to small water systems (those serving populations less than 10,000) in November 2000. In May 2002, EPA is scheduled to promulgate stage 2 of the disinfectant by-product rule and the second long term rule for enhanced surface water treatment based on the results from the ICR. EPA is also in the process of promulgating a ground water disinfection rule since the surface water treatment rules do not apply to systems which rely solely on groundwater.

Endnotes

1. Community water systems serve at least 15 service connections used by year-round residents or regularly serve at least 25 year-round resident. 40 C.F.R. 141.2. Nontransient noncommunity water systems regularly serve at least 25 of the same people over six months of the year. Examples are schools and factories. Transient noncommunity systems, by definition, are all other public water systems. Examples are restaurants, gas stations, campgrounds, and churches.
2. The MRDLGs and MDRLs are:
   
   • MRDLG (mg/L)
   • MDRL (mg/L)
   • Chlorine
   • 4.0 (as Cl₂)
   • 4.0 (as Cl₂)
   • Chloramine
   • 4.0 (as Cl₂)
   • 4.0 (as Cl₂)
   • Chlorine Dioxide
   • 0.8 (as ClO₂)
   • 0.8 (as ClO₂)
3. EPA and stakeholders are also conducting about $100 million in additional research to provide information for these state 2 rules.