EPA sets deadlines for monitoring microbial pathogens in ground water
- By Joe Dischinger
- Jan 01, 2007
Twenty years after Congress directed it to do so, the U.S. Environmental Protection Agency issued regulations requiring public water systems to check underground sources of drinking water for viruses and bacteria. The rule's long incubation gave agency representatives, technical experts, water providers, state governments, and other stakeholders time to collaborate on a flexible and moderate Ground Water Rule (GWR) that will help reduce the spread of infectious disease.
Need for Ground Water Disinfection
Approximately 147,000 public water systems in the United States use ground water sources, supplying drinking water to 114 million people. More than 60 percent of these people receive water that is either not disinfected or is treated to less than 4-log (99.99 percent)inactivation or removal of viruses. A very high level of disinfection effectiveness is required, because EPA has determined that a single virus in 10,000 liters of drinking water can cause disease.
According to the Centers for Disease Control and Prevention, more than half of all waterborne disease outbreaks in the United States between 1991 and 2000 were associated with ground water systems. EPA recently posted on its Web site a collection of research reports, one of which suggests that as many as 16.4 million cases of acute gastrointestinal disease each year may be attributable to drinking water delivered by community water systems. The GWR makes the more modest claim that its implementation will prevent 42,000 viral illnesses and one death annually, but it makes clear that this almost certainly understates the benefits of ground water system disinfection.
Brief History of the Ground Water Rule
The 1986 Amendments to the Safe Drinking Water Act required EPA to issue regulations requiring all public water systems to disinfect their water supplies, whether from surface water or from ground water. EPA began developing the Ground Water Rule (then called the Ground Water Disinfection Rule) in 1987, requiring disinfection by every public water system to address fecal contamination of ground water supplies. Although this across-the-board requirement for disinfection was mandated by the 1986 Amendments, most people who were knowledgeable about drinking water supplies believed that microbes were not a problem in many ground water supplies, and the proposed requirements would be unnecessary at many systems. In 1991, EPA expressed its policy toward protecting ground water as follows: "The primary responsibility for coordinating and implementing ground water protection programs has always been and should continue to be vested with the states." EPA continued to study and discuss the proposed Ground Water Disinfection Rule internally and with working groups of stakeholders for nearly a decade, but no final rule had been issued by the mid-1990s.
In 1996, Congress amended the Safe Drinking Water Act again. In particular, the 1996 Amendments required EPA to develop regulations requiring disinfection for ground water supplies "as necessary." EPA published a proposed Ground Water Rule in 2000 in the Federal Register.
After years of public comment, General Accounting Office review, and further study, EPA made the GWR final in October 2006.
What the GWR Requires
The GWR is designed to identify those ground water systems that are most at risk of fecal contamination, because these systems may be supplying water that contains microbial pathogens. For the first time ever, there is a federal requirement for sanitary surveys of all ground water systems. In certain circumstances, the GWR also requires source water monitoring, corrective action, compliance monitoring, and reporting.
Sanitary Surveys. States must perform sanitary surveys for all ground water systems, including an evaluation of eight separate components:
- finished water storage;
- pumps, pump facilities, and controls;
- monitoring, reporting, and data verification;
- system management and operation; and
- operator compliance with state requirements.
States must complete the initial surveys of most community water systems by Dec. 31, 2012, and those must be re-surveyed every three years thereafter. Surveys of community water systems that meet certain performance criteria and of non-community water systems must be completed by the end of 2014, and every five years thereafter.
The surveys should identify significant deficiencies that, in the opinion of the state, are causing or have the potential to cause the contamination of water delivered to customers. The GWR provides a lengthy list of defects in design or operation that would likely be considered significant deficiencies. These include, but are not limited to the location of a well near a source of fecal contamination (such as a failing septic system or a leaking sewer line); the inadequate application of treatment chemicals; the entrance of contaminants into distribution systems; inadequate cleaning and maintenance of storage tanks; inadequate recordkeeping; the lack of an approved emergency response plan; and the lack of operator certification or training.
Triggered Source Water Monitoring. The rule requires source water monitoring to test for the presence of the fecal indicators E. coli, enterococci, and coliphage. This monitoring of source water is "triggered" in ground water systems that do not already provide at least 99.99 percent (4-log) inactivation or removal of viruses through treatment, if a routine sample taken from the distribution system under the Total Coliform Rule tests positive for total coliform. Upon notice of a total coliform-positive result from the distribution system, the water provider must take a ground water sample from each ground water source within 24 hours, to determine if the ground water is contaminated with the fecal indicators. The compliance date for triggered source water monitoring is Dec. 1, 2009.
Assessment Monitoring. States also have the option of requiring ground water systems to conduct source water assessment monitoring at any time to help identify high risk systems. While the assessment program is up to the states, EPA recommends that states use Hydrogeologic Sensitivity Assessments, data collected under the Total Coliform Rule, and other information to identify those systems that are at higher risk for contamination. The identified systems must take monthly samples and test them for the fecal indicators.
Corrective Action. If a significant deficiency is identified, or if the triggered or assessment monitoring indicates fecal contamination in the source ground water, the GWR requires the public water system operator to implement at least one of the following corrective actions:
- Correct all significant deficiencies;
- Provide an alternate source of water;
- Eliminate the source of contamination;
- Or provide treatment that reliably achieves at least 4-log treatment of viruses.
Compliance Monitoring. All ground water systems that provide at least 4-log treatment of viruses using chemical disinfection, membrane filtration, or a state-approved alternative treatment technology must conduct compliance monitoring to demonstrate effective treatment.
Reporting. If source water monitoring indicates fecal contamination in a ground water source, the water provider must notify the state and the public (so members of the public can take precautions to avoid infection). Similarly, if sanitary surveys identify any significant deficiencies, the provider must inform the public of any that remain uncorrected.
The Bottom Line
EPA has estimated that the cost of implementing the GWR will be a present value of approximately $62 million annually. Drinking water utilities will incur about 81 percent of these costs, and states will incur the remaining costs. EPA estimates that households that receive drinking water from community treatment systems that use ground water sources will experience increased costs of $0.21 to $16.54. The estimate is a calculated average that includes all the systems that will not need to add treatment. The wide range is necessary because systems serving fewer households have higher average annual household costs. If we include only those systems that will need to take corrective actions, EPA estimates the average household cost of the rule will range from $0.45 to $52.38 per year.
States have less than two years to adopt the Ground Water Rule, and ground water systems will be required to implement triggered monitoring (and associated corrective actions) and compliance monitoring by Dec. 1, 2009. EPA has promised to issue guidance documents to help states and water providers comply with the new rule, but these guidance documents are not yet available. Many drinking water systems will want to make changes soon to ensure compliance will be achievable in the near term, and some may need to make budget adjustments to prepare for increased costs, including possibly applying for financial assistance under the Drinking Water State Revolving Fund.
This Waterlawged column originally appeared in the January/February 2007 issue of Water & Wastewater Products.
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