Without it, a person can live for 3 to 4 days, and a city ceases to function in a week or less. When we stop to think about it, air, water quality, and food make up the three-legged stool of basic necessities. We turn on the faucet, take a shower, spray the plants using a garden hose, and rarely consider the water quality, safety, or hazards posed by the fluid that comes out. Where the water comes from, what pathogens are of concern, and how it is treated are subjects we probably learned about once long ago in some environmental ecology course. As the State Toxicologist for Florida’s Department of Health from 2008 to 2011, I encountered a wide variety of human health hazards, but water and its pivotal role in society quickly became apparent. Over the past 30 years, I have practiced as both a public health official and private consultant and have come to one conclusion. The water we rely upon every day and the patchwork of distribution systems, regulations, and technologies used to deliver clean, safe, and reliable water are on the verge of collapse. Unlike roadways and bridges, or even the fragile electrical grid, which we can see and feel when they fail, drinking water systems are obscured and unseen by almost everyone who relies upon them. Even if you get your water from a private well, which much of rural America does (23 million households), you are at risk of receiving contaminated water that fails to meet basic health standards.
Water Quality Misconception
The misperception that water quality is stable and constant is widely held by the public, politicians, and even regulators. The litany of regular and extraordinary events that threaten America’s drinking water supplies is not widely publicized, but they are coming to a head more often. Cities such as Washington, DC, Flint, Michigan, and Jackson, Mississippi have experienced highly public and devastating failures of their water systems and supplies. With the recent disaster experienced by western North Carolina, Asheville, and dozens of small towns and communities in surrounding counties and states, we are seeing fragile municipal systems come apart at the seams. Approximately 1/3rd of the households rely upon private wells for drinking water in western North Carolina, as recently reported by the New York Times. About 30% of the drinking water wells that were tested after Helene impacted the area were positive for E. coli or fecal coliform bacteria. These bacteria indicate contamination from human sewage or animal waste, probably from the floodwaters, but many of these wells may have been contaminated before the storm ever hit. How many people are impacted by well water contamination or from the contaminated municipal water systems is unknown at this time. Private drinking water and irrigation wells are not well tracked, and there is no state or federal database or list of wells.
Chemicals, bacteria, viruses, and even radiological contaminants are recognized by the US EPA as waterborne hazards. The treatment systems and infrastructure to treat and distribute water throughout the US are antiquated and deteriorating. With public attention and money focused on the replacement of lead service lines to homes, schools, and multi-family properties, we are about to literally “un-earth” one of many long-standing problems. The foreseeable impacts of this long-overdue resolution will be discussed in this series.
However, first and foremost, I want to peel back the hidden problems facing America’s drinking water and discuss why the solutions that saved us in the early 1900s must be reconsidered as we move into the problems facing us in the early 21st century.
We’re Adding WHAT to the water!
Sickness and death from drinking water have been a long-time recognized public health issue. You could argue that Public Health owes its beginnings to John Snow removing a public pump handle in London to stop a cholera outbreak in 1854. Since then, city engineers and public health advocates sought out measures to prevent the spread of Cholera and other waterborne pathogens. In 1908, Jersey City became the first municipal water system to continuously inject chlorine (sodium hypochlorite) at “low levels” into its drinking water system. This major change in how drinking water was treated is believed to have stopped outbreaks of typhoid fever, cholera, and numerous other waterborne pathogens. Chlorine and its various derivatives have been pivotal to the control of 20th-century pathogens and the illnesses they caused. It has made public bathing (swimming pools and whirlpool spa tubs) significantly safer for most people and allowed water to be supplied to millions of homes in a substantially safer manner than before. Understanding the history of chlorinated drinking water is critical to understanding the disparate framework of rules, regulations, and testing seen throughout the United States.
With little to no knowledge of the unintended consequences that lay before them, public health officials and water system engineers had found a relatively safe additive that made drinking water systems safer than before. In hindsight, we need to reconsider the reliance upon chlorine and other disinfectants to deliver drinking water that doesn’t cause mass illness and disease. Ultimately, the reliance we have established on chlorine and other disinfectants has come with a myriad of adverse effects that are detrimental to public infrastructure and public health in general.
Chlorine Reliance
Chlorine, the 17th element on the Periodic Table, was first described by Swedish chemist Wilhelm Scheele in 1774 as hydrochloric acid (HCl). Chlorine has been used in industry, warfare, and as a lifesaving disinfectant. Toxicologists view all substances as toxins, with the dose and route of exposure making the difference between a curative or protective substance and one that causes harm or death. Remarkably, free chlorine in drinking water at concentrations below 4 mg/L (ppm) has been deemed safe for drinking water supplies, and at levels above 0.5 ppm, chlorine is usually effective at inhibiting or killing most microbial pathogens. Fortunately, the concentration of chlorine in water that is lethal to humans is about 100 times higher (400 ppm). Chlorine readily escapes water as a gas and rapidly reacts with organic matter, soil, and bacteria, causing it to bind and lose further efficacy.
Fundamentally, chlorine is a very toxic substance that, when used at very low levels in drinking water, can inhibit or kill most, but not all, pathogens. Using chlorine to treat drinking water and control pathogens brings with it risks of cancer-causing byproducts, corrosion of plumbing system equipment and materials, and possibly plays a role in the development of antibiotic resistance of pathogens that are exposed. After 100+ years of using chlorine to treat drinking water systems, its usefulness appears to be approaching the end as the risk from other pathogens is rising. Respiratory pneumonias caused by nontuberculous mycobacteria (NTMs), Pseudomonas, and Legionella have surpassed all other waterborne pathogens combined in their prominence and lethality (CDC MMWR 2024). Similarly, exposure to chemical contaminants such as lead and copper, promoted by chlorine’s corrosive nature, is also increasing risks to public health.
Carcinogens - The downside of chlorine is that it reacts with organic matter in water supplies to create a series of disinfection byproducts (DBPs) that are recognized carcinogens. These carcinogens (trihalomethanes (THMs), and haloacetic acids) have been regulated in US municipal drinking water systems under the Safe Drinking Water Act since 2003. Despite lower exposures, some risk still remains from levels of DBPs that unavoidably remain in the water when chlorine is used to treat municipal water systems.
Another form of chlorine, called chlorine dioxide, that is used to treat some drinking water systems, generates another series of disinfection byproducts, including chlorites, chlorate, and THMs. It is the formation of disinfection byproducts (DBPs) that has been associated with the carcinogenic risks of chlorine rather than the chlorine exposure directly.
Corrosion - The way that chlorine works is that it forms hypochlorous acid in water when pH (acidity) is favorable. This chemistry can also result in the corrosion and leaching of lead (Pb) from lead pipes, lead service lines, and brass valves and fixtures. Over time, especially if anti-corrosive chemicals are not used, corrosion caused by chlorine and other disinfectants can attack the interior wetted surfaces of plumbing materials and leach lead into the water, exposing users who consume the water. Chlorine is not the only oxidizing disinfectant that has been recognized to accelerate corrosive processes and potentially release lead from plumbing materials. Adding chemical disinfectants to inhibit pathogens and other bacteria generally promotes corrosion and complicates attempts to prevent corrosion and conserve water.
Antibiotic Resistance – Reports of antibiotic resistance in bacterial waterborne pathogens have been linked to chlorination of water. It is commonly recognized that resistant bacteria normally develop in the human body or animals that are chronically treated with low doses of antibiotics. This process allows surviving bacteria to adapt and develop resistance. Environments outside of the human body where adaptations to the genetic code of bacteria and fungi can result in antibiotic drug resistance are less well understood. Ironically, the same genes in bacteria that enable them to resist the damaging effects of chlorine also play a part in antibiotic resistance. Some studies have found correlations between resistance to antibiotics and chlorine resistance in bacteria replicating in aquatic environments. Other researchers have concluded that the correlation is due to co-selection of certain bacteria that first developed chlorine tolerance. A worrisome trend is that the three major pathogens responsible for over 75% of the direct medical costs from diseases caused by waterborne pathogens (2.6 billion in 2014 alone) are considered chlorine-tolerant organisms (NTMs, Pseudomonas, and Legionella).
The rise in case prevalence and associated healthcare costs may be early warnings of the confluence of factors and a shift in the microbiome of building water systems. Chlorine-tolerant microbes finding favorable habitats in deteriorating municipal and premise plumbing systems may mean that more people are being exposed to these pathogens. If these pathogens are developing resistance to both chlorine and antibiotics, an emerging crisis may already be unfolding.
An Alternative Water Quality and Safety Strategy
An Alternative Strategy is Needed - It is chlorine’s reactive properties that bring its benefits and its drawbacks. In many ways chlorine can be viewed as analogous to chemotherapy drugs used to treat certain human cancers. They can be lifesaving therapies used when nothing else works. However, they extract a price for their miraculous abilities. They cause damage to the body’s cells, can destroy the immune system and allow life-threatening infections, and ironically can even increase the risk of causing another cancer. However, we would never propose using preventive low-dose treatments with chemotherapy drugs to “prevent cancer”. This absurd approach has however been the primary way we have controlled waterborne pathogens in US municipal drinking water systems for well over 100 years. We are likely just now experiencing the long-awaited, but inevitable adverse effects of this approach.
Adding toxic and corrosive chemicals to our drinking water has been the standard for over 100 years for controlling waterborne pathogens in municipal drinking water distribution systems. However, treating bacterial contamination located within the plumbing lines that distribute cold and hot water from the water meter to the faucets, showers, spigots, and other typical uses, referred to as the premise plumbing system poses a whole different set of challenges. The technologies, chemical treatment, and approaches used for large volumes of water treated by a municipal water system are not easily scalable for use in smaller building water systems. Once water is introduced to a building and treatment is needed long term treatment and control requires a different approach. Preferably building water systems should use an approach that is non-toxic and doesn’t promote corrosion or produce carcinogenic byproducts. Alternative pathogen control strategies will be the subject of my next installation.