Crystal clear

Cynthia Dougherty, director of the Environmental Protection Agency’s Office of Ground Water and Drinking Water, talks to US Infrastructure about the state of the nation’s water infrastructure, effective protection against microbial pathogen contamination and violations of the Safe Drinking Water Act

“Better quality source water is an essential component of any program to improve drinking water quality”
-Cynthia Dougherty

What are the current methods available for protecting against microbial pathogens in public water systems and what advances can be seen in the technology used for preventing contamination?

There are two general approaches for addressing pathogens in source water. The first is physical removal/filtration, in which the pathogen is removed from the water. There are a wide variety of existing, proven technologies that are used - the choice is up to the individual public water system (with State consultation). Systems select particular technologies based on many factors, such as source water quality (level and variability of turbidity, temperature, pathogens, contaminants other than pathogens, levels of organic and inorganic materials, etc.), existing (in-place) treatment, regulatory requirements that apply to the system, cost, operator expertise, availability of land for new processes, water quantity needed, and ability to dispose of residuals (sludge, reject water from membrane processes, etc.). Widely used removal technologies include conventional filtration (including flocculation, coagulation, sedimentation), direct filtration, slow sand filtration, diatomaceous earth filtration, cartridge and bag filtration, membranes (reverse osmosis, nanofiltration, ultrafiltration, microfiltration) and riverbank/bank filtration. Each of these processes have advantages and disadvantages.

The second is disinfection/inactivation, in which a chemical disinfectant (chlorine, chloramine, ozone, chlorine dioxide) or ultraviolet rays are used to "kill" the pathogens, rendering them non-infectious. As with filtration, the selection of technology is up to the system, in consultation with the State. Each of the processes has advantages and disadvantages. Systems use many of the same considerations as they use to select a filtration technology.

Nearly all surface water systems (and some ground water systems) use a combination of both filtration and inactivation. This provides a multiple barrier and better addresses the wide variety of pathogens and other contaminants. These technologies are designed to control not only regulated pathogens, but unregulated pathogens.

Finally, surface water systems and some ground water systems (especially larger ones) maintain a disinfectant residual within the water distribution system to control microbial regrowth. This residual, in addition to a well-designed flushing program, proper storage tank operation, pipe maintenance/repair and replacement, and good design and construction, help to ensure that the water produced at the treatment plant maintains its quality on the way to the consumer.

Just as the past 20 years have brought new/improved processes (e.g. membranes, ultraviolet disinfection) and more effective ways to operate existing technologies, the next 20 years will bring more progress. In addition to new technologies, there is an increasing awareness of the need to reduce the levels of both regulated and unregulated contaminants entering our water sources. Better quality source water is an essential component of any program to improve drinking water quality.

Do you believe that heavier environmental disinfection systems are needed to protect drinking water from microbial infection?

Two EPA rules finalized in 2006 - Long Term 2 Enhanced Surface Water Treatment Rule (LT2ESWTR), which applies to surface water systems and those using ground water under the direct influence of surface water; and Ground Water Rule (GWR), which applies to ground water systems - will provide greater protection from pathogens.

Under the LT2ESWTR, systems were required to monitor to determine whether pathogen levels were higher than levels typically seen and already protected against by earlier rules. Systems with higher pathogen levels are required to install additional treatment or use a better quality source water.

Under the GWR, systems not already providing a high level of pathogen treatment are required to evaluate their source water to determine whether additional treatment is required to address contamination. Systems in compliance with these and other drinking water rules provide properly treated water to their consumers. While these and earlier rules provide a high level of protection, EPA will continue to evaluate the need for additional pathogen protection under the review provisions of the Safe Drinking Water Act.

How effective has the Ground Water Rule been in achieving its objective?

The Safe Drinking Water Act provides three years for implementation of regulations under most circumstances (including for the Ground Water Rule). In accordance with the SDWA requirements, the Ground Water Rule (GWR) provided States and systems time to implement the rule before compliance to determine how the rule applies, conduct analyses, fund and make capital improvements needed for compliance, and get the upgrades operating properly. 

As a result, in December 2009, public water supply systems began the additional compliance monitoring required under the GWR. This monitoring is designed to identify whether source waters are fecally contaminated. While there is no compliance information available yet on GWR effectiveness, many systems and States have spent the past three years evaluating their water sources to determine whether corrective actions are needed and making necessary changes. 

According to a New York Times analysis of federal data, more than 20 percent of the nation's water treatment systems have violated key provisions of the Safe Drinking Water Act over the last five years. Is this correct and if so how has this been allowed to happen?  What is the EPA strategy for ensuring that violations are kept to an absolute minimum in the future?

The vast majority of Americans receive water that is safe to drink. The statistic cited by The New York Times includes a range of violation types, many of which don't indicate an exposure to dangerous contaminants. For example, many drinking water standards are based on health effects that occur over the long term, and a single violation does not represent increased risk. Other violations are indicators that systems may need to take additional action but do not necessarily indicate that a contaminant has been detected at dangerous levels. 

We still have work ahead of us, though. 96 percent of health-based violations occur at systems that serve less than 10,000 people. These systems face unique challenges in providing safe drinking water. A lack of effective system management, trained operators and financial resources often leads to compliance problems. Access to safe drinking water should not be based on ability to pay and we have developed a new Agency approach to ensure that small system customers get the full public health protection of the Safe Drinking Water Act. There is no single solution to the challenges small systems face and a variety of strategies will need to be employed, but EPA believes that robust use of the tools provided in the SDWA can achieve our goal that all Americans have safe drinking water.

The new approach will focus SDWA resources on the specific challenges small systems face, from regulatory compliance to sustainability. The components of this plan are designed to facilitate use of SDWA tools to achieve the greatest benefit, by reducing difficulties and providing states with active oversight, guidance, and technical assistance. State programs are the key to this approach and we will work to help them link federal infrastructure funding to public health improvements and target technical assistance to strengthen the capacity of individual water systems. EPA has also developed a new Enforcement Response Plan in order to use enforcement tools most effectively and to better target enforcement actions to systems in significant non-compliance.

Weathering the storm

Cynthia Dougherty explains what measures are in place to protect against contamination following events such as floods and hurricanes.

Natural disasters given their potentially overwhelming destructive power can defeat even the most robust plans to protect sources of water and the critical infrastructure that treats, stores, and delivers this water to communities. Therefore, EPA's water security program emphasizes a multi-barrier approach in preparing for such events, which includes both prevention and response/recovery activities. Preventive actions, for example, could consist of constructing a berm around a treatment plant or relocating infrastructure outside of a potential flood zone.

Recovery and response actions, for example, could involve installing back-up power generators at pump stations and implementing the facility's emergency response plan. Also, EPA and partners have through training and other forms of assistance encouraged states and their water systems to form mutual aid and assistance compacts, called Water Agency Response Networks, under which water systems provide emergency personnel equipment, and even water to other water systems. Although the efficacy of these preventive and recovery countermeasures will vary depending on a range of factors, the impacts from climate change likely will pose an increasing challenge to the public health mission of many water systems.

Safety first

The condition of the drinking water infrastructure in the United States in 2009 has allowed 89 percent of community water systems to deliver water to their customers that met all health-based standards all year in 2008. Ninety-two percent of the US population receives these drinking waters meeting all health-based standards. However, the capital investment needed to maintain this service into the future is great.

Treatment plants typically have an expected useful life of 20 to 50 years before they require expansion or rehabilitation. Pipes have lifecycles that can range from 15 to well over 100 years. Historically, pipe installation in major cities was greatest between 1960 and 1970 and has since declined. In 2002, EPA projected that we are currently on a path of increasing need for pipe replacement and rehabilitation and the need is expected to rise until about 2040. Additionally, treatment plants will need to be replaced and even upgraded for treating more recently identified contaminants. The latest Drinking Water Infrastructure Needs Survey identified a need of $335 billion for the 20-year period 2007-2026. Of this amount, 60 percent will be needed for transmission and distribution, 22 percent for treatment, 11 percent for storage, six percent for source, and less than one percent for other infrastructure. 

The Drinking Water State Revolving Fund (DWSRF) is an important tool through which the EPA and the states provide funding to utilities for infrastructure projects. Since its inception in 1997, the DWSRF has provided almost $15 billion in low-interest loans to public water systems. The new administration recognizes the importance of drinking water infrastructure investment not only to provide public health protection but also to provide the foundation for future economic growth and development. Congress significantly increased DWSRF funding in FY2010, and the American Recovery and Reinvestment Act put nearly $2 billion in additional funds toward infrastructure needs.  These funds take a big step in the right direction, but the infrastructure investment need is still substantial.  Meeting this need will call for a local, state, and federal partnership. 

To be sustainable, a system must have the capacity to address existing needs as well as be prepared for the long term, so they can continue to provide safe water today, tomorrow, and in the future. Several key aspects to making this happen are incorporating pricing strategies that recover the full cost of providing service, and asset management to minimize operating costs and plan for future needs. EPA is working to help systems address these issues and the Agency is working to help ensure that all water systems have the resources and support necessary to build financial, technical and managerial capacity.  Within this framework, we provide training, technical assistance, and other tools to promote sustainability and the protection of public health.