The opening of the Columbia Heights Water Treatment Plant disappeared in the vast news shadow of Hurricane Katrina, but it marks a sea change in the treatment of drinking water. Using a technology known as ultrafiltration, it meets a standard for water treatment far beyond that set by the EPA. It replaces a plant built in 1913, three years after an outbreak of waterborne typhoid fever killed 185 people in Minneapolis. Most plants around the United States look far more like the plant completed in 1913 than the one that went online in 2005. Other enlightened utilities around the country have concluded in the wake of the outbreak that it is better to move ahead of the EPA than to rely entirely on their standards. From Racine, Wisconsin, to San Antonio, Texas, utilities have built or are planning to build plants similar to the one on Columbia Heights.
Forward-thinking water suppliers are also reconsidering their relationship with one of their oldest and dearest friends, chlorine. Accumulating evidence about the possible risks from the by-products of chlorination, together with the appearance of pathogens that resist chlorine, have prompted a new look at our reliance on chlorine. A recent study suggesting that the cancer risk may arise from inhalation rather than ingestion of volatile by-products makes this problem even more daunting. Ozone, the most prominent alternative, can inactivate cryptosporidium oocysts and under most circumstances it appears to produce far fewer toxic by-products than chlorine. Water suppliers in Europe have a hundred years of experience with ozone since its first use in Nice, France, in 1906. Today, thousands of water treatment plants in Europe and Japan rely on ozone, and, somewhat belatedly, many American cities have taken steps to follow suit. Milwaukee now treats its water with ozone. In the summer of 2005, the MWRA flipped the switch to turn on massive new ozone generators to treat Boston’s drinking water. These utilities must still add some chlorine to protect the water from contamination as it passes through the water pipes, but in minimal quantities compared with plants that rely on chlorine exclusively. We can expect more utilities to move away from chlorine as a primary method for disinfection as experience with ozone and research on other alternatives increase and improve alternative methods for disinfection.
The treatment plant that supplies water to the EPA Drinking Water Research Laboratory in Cincinnati passes through thick beds of charcoal after trickling through the more conventional sand filters at the city’s Miller Treatment Plant on the Ohio River. The charcoal sucks up chemical contaminants like billions of tiny black sponges. Concerns about the impact of a chemical spill on the water supply prompted the installation of the carbon filter, which removes chemical contaminants using the same technology employed by many home water filters. Conventional water filtration as relied on by most American cities was never intended to remove chemical contaminants from drinking water, and for most utilities chemical removal remains a low priority.
Modern industry produces and releases tens of thousands of different chemicals. Most, if not all, of them find their way at some level into our water supplies. EPA regulates only the ninety-six most common or most toxic chemicals in drinking water. Regulators focus on single chemicals as they evaluate risk and set standards. Logistics and costs tend to limit risk assessments to a small set of health outcomes, primarily cancer. It is impossible to look at the full range of human diseases when evaluating health risks. As a consequence, we make the implicit assumption that unexamined risks do not exist.
On several counts we may find a need to reexamine our view of chemical risk in general and chemicals in drinking water in particular. An increasing body of evidence indicates that chemicals in the environment may disrupt the subtle chemical communication systems in our bodies in ways never previously considered, with a broad range of possible health effects. Other research suggests that developing embryos and young children may be particularly vulnerable to these effects. Finally, emerging evidence about the combined effect of chemicals in small concentrations, particularly the thousands of unregulated chemicals, raises serious concerns about our entire approach to chemical regulation and may force a reexamination of our relative inattention to chemical contaminants in drinking water.
MULTIPLE BARRIERS
A patient diagnosed with tuberculosis routinely receives a combination of three antibiotics, a treatment regimen known as triple-drug therapy. These drugs are not always essential to kill the organism responsible. Rather they ensure that if some of the tubercle bacilli have developed resistance to one of the drugs they will be eliminated by the other drugs.
Triple-drug therapy is used to prevent the widespread emergence of strains of Mycobacterium tuberculosis that are resistant to one or two antibiotics. If we use a single drug, we would soon find that most tubercle bacilli are resistant and the drug would become useless. If we used one drug at a time and waited for resistant strains to emerge before using the next drug, we would eventually find that none of the three drugs would be effective and we would have no protection against one of the worst scourges in human history.
This in many ways is similar to an approach to water treatment that the American Water Works Association refers to as the multiple barrier method, which is comprised of source water protection, coagulation with sedimentation, filtration, and disinfection. A pathogen might find its way past one or even two of these barriers, but it is highly unlikely that large numbers of pathogens can make it through all four of these barriers. Improving individual barriers and using those barriers in combination are essential to providing and maintaining safe drinking water.
The parallels between tuberculosis and waterborne disease grow more chilling when we move to the poorest regions of the world. High infection rates, limited access to care, and the inability to afford multidrug therapy make the explosive emergence of resistant tuberculosis a constant threat that all too often becomes real. Similarly high rates of diarrheal diseases, inadequate or nonexistent sewage treatment, and limited or nonexistent treatment of drinking water, together with the routine mingling of animals and humans, makes the emergence of new waterborne diseases a dangerous possibility. The use of single barriers for water treatment in these circumstances will encourage the emergence of waterborne pathogens that are difficult to remove from drinking water.
The EPA pays close attention to our treatment plants and has a multitude of regulations that apply to the water flowing out of them. Even if those regulations do not require the use of multiple barriers, they implicitly encourage the practice. Those rules, however, have a fundamental limitation: they do not directly regulate the water we drink. Almost all the regulations that apply to drinking water end at the boundaries of the treatment plant. As water crosses the fence line, it enters an obscure subterranean world ruled by rust, slime, and history. That dark and corroded underworld offers uncounted and unseen opportunities for the degradation of our drinking water. Other than a bit of leftover chlorine, nothing stands between a pathogen in the pipes and the glass of lemonade your child is mixing in the kitchen.
THE PIPES
America’s drinking water courses through millions of miles of water mains, the unseen vasculature of a modern city. Thirteen hundred miles of those pipes lie buried beneath the streets of Washington, D.C. In the summer of 2004, Jerry Johnson, the man responsible for those pipes and the water inside them, had a plumbing problem.
Over two thousand years ago, the plumberii (literally, lead workers) of the Roman Empire began to lay pipes of lead rather than wood or clay. Lead would remain a mainstay of plumbing for the next two millennia. The use of lead pipes and lead solder was not banned in the United States until 1986. In every major city in the United States, one can find thousands of homes with lead pipes connecting them to drinking water mains. Water, with its remarkable ability to dissolve, carries lead to the faucets of those homes. Older cities, such as Washington, D.C., have the most lead. In the first six months of 2004, one in ten homes tested in the city had lead levels above 74 parts per billion (ppb), almost five times the EPA limit of 15 ppb. Research suggests that blood lead lev
els above 10 ppb may adversely affect the development of a child’s brain. Levels above 45 ppb require urgent medical treatment.
Jerry Johnson had had problems meeting the EPA lead limit since it was introduced in 1996. When the EPA ordered that he solve the problem, Johnson and his advisers turned to a method that had been employed by many other utilities in the same situation and they began to add phosphoric acid to their drinking water. If all went well, the phosphoric acid would form a coating on the interior of the lead pipes that would keep the lead from leaching into the water.
Within weeks Jerry Johnson had a new problem. The city’s water mains, old and made largely of cast iron, were far from pristine. Thick deposits of iron oxide formed mountain ranges of hardened rust along the interior of the pipes. These deposits narrowed the pipes to a fraction of their original diameter and provided billions of hiding places for bacteria. Even the smoothest pipes are lined with a layer of slime and microorganisms known as the biofilm. In these old pipes, like the pipes in most water utilities, the biofilm teemed with microorganisms. The phosphoric acid loosened the biofilm and flooded the system with bacteria.
Biofilms can harbor a broad range of microorganisms and can protect them from chlorine. This microscopic menagerie routinely includes the pathogen responsible for legionnaire’s disease as well as a strain of tuberculosis that can cause severe disease among susceptible individuals, particularly those with lung disease or weakened immune systems. Many bacteria form spores or other dormant forms that are resistant to disinfection and can hide in the biofilm. These include E. coli O157:H7, the deadly organism responsible for the Walkerton outbreak. These spores are rarely released in large enough numbers to cause disease outbreaks, but their presence should give us pause.
Although the problem with the water in Washington was solved and no outbreak was detected, the incident hints at some of the problems hidden in the pipes that carry our water. The pipes are riddled with leaks that can be an open door for microbes. The complex connections among those pipes can, under certain conditions, pull contaminated water into the system. The simple fact that these systems have been built and rebuilt by thousands of people over the course of a century or more makes some of these problems inevitable.
In Washington, as in most large cities, the pipes themselves are often more than a hundred years old. Periodically utility workers maintaining these pipe networks even unearth sections of wooden pipe. In 2006, about 20,000 miles of water mains in the United States will need replacement. By 2020 we will need to replace 100,000 miles each year. The EPA has estimated that simply maintaining our water distribution systems in the United States will cost $100 billion in today’s dollars over the next twenty years as we replace about 1 million miles of pipes. After that it gets expensive. During the twenty years after 2026, we will need to replace 6 million miles of pipe, at costs in excess of half a trillion dollars.
A peculiar bit of manufacturing history is helping to drive this problem. The first iron pipes were installed in the nineteenth century and have now reached or exceeded their design life of 125 years. About twenty-five years later, manufacturers learned to make a thinner pipe. The thin walls made it less expensive and easier to work with, but reduced the design life to about one hundred years. Another twenty-five years passed before the introduction of a new pipe with still thinner walls. It’s design life? Seventy-five years. As if part of some grand, unintelligent design, this pattern of manufacturing innovation has synchronized the decay of all three different types of pipe such that they will all reach the end of their useful life at roughly the same time.
The invisible decay of our water pipes is widely seen within the industry as the Achilles’ heel of our system for drinking-water treatment. Generating the political and public support for spending hundreds of billions of dollars to replace rotten pipes will pose a daunting challenge. Water supplies operate largely out of the public view. In the drinking-water industry, public attention almost always implies a problem.
The sheer unsexiness of running dirty water through sand makes generating the political support necessary for vast capital expenditures on drinking water difficult. New treatment plants at least provide the opportunity for a ribbon cutting and a name over the entrance, features capable of generating political support. If water purification lacks political sex appeal, then the rusting cast iron pipes beneath our streets have all the allure of a fungal infection. Replacing them disrupts traffic and costs money. To make matters worse, no one, to my knowledge, has ever expressed interest in having a stretch of buried pipe named in his or her honor.
Although most utilities are moving forward with improvements in their distribution systems, the EPA has projected a major shortfall in spending in this area. According to the National Academy of Science, this shortfall is likely to get worse over the next forty years. The political impetus to tighten drinking water regulations generated by the Milwaukee outbreak has already faded. Let us hope that it does not take another major disaster to generate the public will necessary to fix our leaky pipes.
Even if we could replace all our water mains tomorrow, another sort of problem, a relatively new problem, would remain. Water distribution systems by definition provide large populations over large areas with access to drinking water. Until recently the openness inherent in this system has seemed to have few negative consequences. Recent events have radically changed that perception.
THE CONSUMER
In the shadow of Seattle’s Space Needle, a blue-green butterfly tattoo flutters on the belly of a teenage girl as if seeking to escape. With one hand she adjusts the controls on her iPod. In the other she holds a bottle of Fijian bottled water. When I ask her why she drinks it, she pulls on a strand of long brown hair before answering, “Like, it just tastes better.” I ask if she thinks it’s safer than tap water. She takes a final sip, and tosses the empty bottle into the trash. “Totally.”
She is not alone. That clattering sound you hear is the drumbeat of the nearly 50 million empty water bottles Americans toss into trashcans and recycling bins every day. Whether for reasons of taste, safety, convenience, or style, Americans like their water in a bottle. Every year, they consume more than 7 billion gallons of bottled water, a number that is rising by 8 percent per year. On almost every count, this is a dubious choice.
The problems begin with the bottles themselves. Their production requires more than two billion pounds of plastic per year, which translates into millions of barrels of oil consumed and a steady release of toxic waste into the environment. The manufacture of a single bottle requires more water than the bottle will ultimately hold. The transport of these bottles over hundreds or even thousands of miles by ship, train, and truck further adds to the disproportionate ecological impact of bottled water.
Even if we set aside concerns about the environmental impact of the bottles, the water inside may not offer the benefits we imagine. Despite the fact that it costs almost a thousand times more than tap water, there is no guarantee that bottled water is safer. Bottled water is less closely regulated than tap water and is not required to meet stricter standards for purity. In fact, a major portion of bottled water in the United States is nothing more than tap water in an expensive bottle. To be sure, many brands of bottled water are superior to tap water and can offer a valuable alternative, particularly when traveling or after a local disaster threatens the water supply. But economically, environmentally, and in many cases even with respect to disease prevention, they fall short as a replacement for piped water.
MANAGEMENT
When Stan Koebel was asked for the cause of the Walkerton outbreak, he said simply, “Complacency.” The staunch belief in the adequacy of the status quo and the dismissal if not outright derision of those who challenge the prevailing belief has, from the time of John Snow through the present, set the table at which disaster dined. The drinking-water industry needs a sea change in attitude. There are many forward-thinking people within the drinking-water industry, but there are
far more, particularly at smaller utilities, who resist change.
Both public health and drinking water treatment were born amid the cholera-and typhoid-contaminated waters of the nineteenth century, but in the years since these twin disciplines have grown far apart. They speak far too rarely and when they do they seem to speak different languages. This distance occurs in part as a consequence of the relative success of drinking-water treatment in the industrialized world and the fact that the application of epidemiology, as the fundamental science of public health, to drinking water has almost always focused on major failures of drinking-water treatment. The appearance of public health personnel at a water treatment plant implies a problem.
There are three ways in which the public health community can and should have a renewed and revised role in the maintenance of drinking water safety. First, the public health and drinking water treatment communities must maintain a constant dialogue, even if it at times becomes adversarial. Improved, ongoing, active waterborne disease surveillance could be a key part of this relationship. A proactive surveillance system would not only give the public health community a legitimate, ongoing oversight role, but it could also provide valuable feedback to the drinking-water industry with respect to any undetected problems in the water supply.
Second, the public health community must be allowed full access to the workings of the water companies. Secrecy has never served the drinking-water industry well. Whether the silence covers turbidity spikes in Milwaukee or E. coli in the water of Walkerton, public knowledge is the last, best defense against disaster. Since 9/11, a cone of silence and secrecy has descended on the drinking-water industry. Much of the publicly available information about treatment plants and distribution systems has simply disappeared from view. Some of this secrecy is understandable and some of it is even desirable, but when taken to extremes, the instinct to conceal can pose more danger than the terrorists. For example, when the federal government, after intense prodding by the environmental lobby, funded a study of possible sources of contamination upstream from drinking-water intakes, the industry responded by declaring the results of the study secret, since it could reveal the location of the water intakes (locations that are often widely known and even marked on local maps), because terrorists might use the information. This growing secrecy makes the oversight by the public health community even more essential. Of particular concern is the proprietary view of information taken by the private companies that have begun to take over water supplies, particularly in smaller communities.
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