How is drinking water supplied in the United States?
More often than not, we take clean water for granted. For most of us, when you turn the faucet, it flows amply. What we forget is that clean water is a shared resource. Cities, agriculture, industries, and power plants need water. So do aquatic wildlife that we depend on food. These are all part of the natural resources we all need on this planet to survive. Water systems do not follow political boundaries and are an inherent part of the global ecosystem that we depend on.
In the United States, a public water system may be publicly or privately owned. The US Environmental Protection Agency (EPA) regulates public drinking water systems (of which there are over 150,000) in the US. Public water systems provide drinking water to 90% of Americans. Roughly 300 million Americans get their water from the public supply system.
The EPA defines three types of public water systems:
- Community Water Systems (CWS) – a public water system that supplies water to the same population year-round
- Non-Transient Non-community Water Systems – a public water system that regularly supplies water to at least 25 of the same people at least six months per year, but not year round. Some examples are schools, factories, office buildings and hospitals which have their own water systems
- Transient Non-Community Water Systems – A public water system that provides water in a place such as a gas station or a campground where people do not remain for long periods of time
For the purposes of this article, we will discuss community water systems. (Please note, community water systems is a “Term of Art.”) There are about 52,000 community water systems today. It is important to note, that just eight percent of all community water systems (4,132) serve 82% of the US population. Although ground water supplies nearly 80% of the systems, more than two-thirds of the population drink from community water systems that use surface water.
“Rights of use” for water in the US
Water rights in the US is a complex matter. Water rights in the US are largely defined on a state by state basis. As a result, each state is responsible for the permitting process. (There are federal reserved water rights for national wildlife refuges, Native American reservations, forests and military basis.) In the US there are two doctrines that govern water rights.
- Riparian doctrine – covers the eastern part where water is abundant
- Prior appropriation doctrine – covers the western part of the US where water is much more scarce.
For those states that follow the riparian doctrine, based on English common law, openers are permitted to make reasonable use of water where their land borders a body of water, so long as it does not unreasonably interfere with other users. Western states like Colorado, follow the prior appropriation doctrine. This means that the first person to use the water or divert water can acquire individuals rights or priority.
California is one of the few states where both riparian and prior appropriation systems are used. This dual approach is problematic as demand from the state’s growing population must increasingly compete with the state’s agricultural sector. California’s farms produce $47 billion in agricultural products. The state grows nearly half of the country’s fruits, nuts, and vegetables.
According to the US Geological Survey (USGS), overall water consumption in the US has fallen since 1980. However, urbanization, land use change, and changing precipitation patterns are making water shortages more frequent in parts of the country. The EPA notes that between 2000 and 2015, up to 70% of U.S. land experienced abnormally dry climate at some point in that time frame.
Consider the Chattahoochee River, which flows from Georgia down to Florida. The river is a major source of fresh water and power for millions of people. Four Federal dams on the river generate clean energy. The Chattahoochee River also flows through Atlanta. And as Atlanta grows, less water will be available for those living downstream in Alabama and Florida.
There are no easy solutions when it comes to water management. It requires that everyone focuses on water conservation and water efficiency.
There are two sources for our drinking water: surface and ground. Surface water comes from streams, rivers, lakes, and reservoirs. Ground water comes from underground aquifers and is procured through the drilling of wells or pumping. Both sources obtain their water from rain or snow melt. It is important to note that 68% of the population that use community water systems depends on surface water.
How is water treated so that it is safe to consume?
The water is withdrawn and treated by either governmental or private utilities. Treated water undergoes the following steps:
- Water is chemically treated to remove particulates from the water (a.k.a coagulation and flocculation)
- Sedimentation, where particulates in the water clump and settle.
- Filtration using sand, gravel, and charcoal removes dust, parasites, bacteria, viruses, and chemicals.
- Disinfection using chlorine and chloramine to kill remaining pathogens.
How are water contaminants classified?
While lead is among the most toxic of pollutants, there is a diverse category of water contaminants. Under the National Primary Drinking Water Regulations, the EPA regulates over 90 contaminants and they are classified as:
- Inorganic chemicals (include metals)
- Organic chemicals
- Disinfectant byproducts
Most municipal and large water systems do not have problems meeting water safety standards. However, smaller water systems that serve no more than a few thousand citizens are more likely to be noncompliant. These systems serve 38 million or 12% of the US population.
How do contaminants get into the water?
While accidents and natural disasters cause water contamination, pollutants can enter the water supply in a number of natural and unnatural ways. Natural leaching from rocks releases elements like arsenic, radon, and uranium into the ground water.
For example in the US elevated concentrations of arsenic in the ground water are found in the West, the Midwest, parts of Texas, and the Northeast. In 2013, the EPA found arsenic levels to exceed the federal limit of 10 parts per billion for 55,000 Californians. In addition to several types of cancer, chronic exposure to arsenic leads to skin lesions, neurotoxicity, diabetes, and developmental effects.
However, most water pollution is human-induced. Industries, sewer overflows, and malfunctioning wastewater treatment systems are major sources of contaminants. Chemical and microbial pollutants can enter the soil and rock, pollute the aquifer, eventually the well.
Agriculture and land use changes also release contaminants into both ground and surface waters. These include fertilizers, pesticides, animal waste, and biosolids. The results include fecal contamination as well as nitrate leaching, which induces toxic algal blooms.
Water and sanitation
Sewage contains many types of germs. The E. Coli bacteria in among the most commonly found in human and animal waste. Scientists analyze water samples for presences of E. Coli to determine if there is contamination from sewage or animal waste.
There are up to 32 million incidences of diarrhea, upset stomach, and vomiting due to waterborne illnesses in the US each year. The Center for Disease Control lists the following contaminants as the top ten contaminants for outbreaks in public water systems: Giardia, Legionella, Norovirus, Shigella, Campylobacter, Copper, Salmonella, Hepatitis A, Cryptosporidium, and E. Coli or excess fluoride.
Globally, at least 1.8 billion people worldwide drink fecally contaminated water each year, according to the UN. According to WHO, “contaminated water and poor sanitation” in developing countries cause diarrhea, which kills half a million people each year.
Climate change and drinking water quality
The Intergovernmental Panel on Climate Change (IPCC) states that climate change will drive more frequent and intense droughts and floods in the years to come. Droughts will force farmers to pump more ground water for irrigation, resulting in elevated levels of nitrates in the remaining water. Exposure to concentrated nitrates is dangerous to animals and humans alike.
Floods can disrupt our municipal sewage systems and wastewater treatment facilities, contaminating water with agricultural or industrial chemicals. A number of Superfund sites in Houston, like the San Jacinto River Waste Pits, was flooded during Hurricane Harvey.
Floods can also spread illnesses by facilitating the growth and transport of pathogens, including intestinal bacteria such as E. coli, Salmonella, and Shigella; Hepatitis A Virus; and germs of typhoid, paratyphoid, and tetanus. As North Carolina found out after Hurricane Floyd in 1999, floods spread fecal matter by overwhelming sewers and waste treatment facilities. Similarly, in 2005, officials found fecal contamination from the flood following Hurricane Katrina, consistent with stormwater events.
What other risks does our water supply face?
The EPA tracks a variety of contaminants as defined in their list of Contaminants of Emerging Concern (CECs). These pollutants include pharmaceuticals and personal care products (PPCPs). For example soaps, shampoos, and lotions, as well as drug compounds like antibiotics and steroids. A USGS study shows that detectable amounts of one or more medications in 80% of the water samples.
Among organic contaminants, dioxin ranks as among the most toxic. They are a class of compounds that are not only carcinogenic, they cause liver impairment, cardiovascular disease, and impaired immune function. Dioxin is produced as a by-product of industrial processes like smelting, paper bleaching, and the manufacturing of pesticides. Incomplete burning as waste incinerators is also one of the biggest sources of dioxin. Because the molecules are so stable, they persist in the environment for years and move up the food chain.
Another example is perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA), which the Air Force used as flame retardants. These chemicals have contaminated the ground water and water supply on air force bases. Evidence of their links to organ damage, birth defects, and other illnesses led the Air Force to adopt alternative firefighting agents.
It is important to note that sewage treatment plants are not designed to treat dioxins, flame retardants, and CECs. These require special chemicals and treatment processes that many municipal water systems are not equipped to handle. Many of these contaminants are known carcinogens and endocrine disruptors, which alter the normal functions of hormones. These contaminants have impacts on humans, as well as wild and aquatic life. As such, it is important to ensure that our waterways and estuaries are not contaminated by these chemicals in the first place.
Lead in the Water: The Flint Crisis
Safe drinking water is necessary for human health and wellbeing. According to the EPA, drinking water in the US is among the safest in the world. However, the water crisis at Flint Michigan (population 100K) in 2016 highlights the vulnerability of the country’s drinking water supply (click here for a step by step timeline).
In 2014, the city managers stopped buying water from Detroit and instead drew water from the Flint River. The corrosive water of Flint resulted in the leaching of lead from the pipes. City managers did not add the required anti-corrosive. Despite complaints from residents and the publishing of Virginia Tech’s water study, city managers denied there was a problem. However, lead levels reached at least 20 times the EPA limit of 15 parts per billion. At these concentrations, lead causes long-term or permanent developmental damage to children.
In January of 2016, President Obama declared an emergency ordering relief. While the emergency was declared over in August, the water crisis spurred Congress to authorize water projects across the country. $170 million was allocated to address lead in Flint’s drinking water, including funds to replace lead pipes.
Can a crisis like Flint’s occur again?
Lead pipes are no longer used for water piping; however, the American Waterworks Association estimates more than 6.1 million lead-containing lines are still in service. These pipes serve up to 22 million people. To prevent leaching from these pipes, utilities must monitor and control the water chemistry. At the right pH and concentration of minerals, a protective layer forms on the inside surface of the pipes. This prevents metals like lead from dissolving into the flowing water.
Water contamination is not limited to lead piping. The EPA lists industrial and mining sources as contributors of water pollution. Coal-fired power generation, which is already under scrutiny for emitting toxic pollutants into the air, releases by-products that can pollute water.
The US generates over 100 million tons of residual ash from coal burning each year. The ash, which contains arsenic, mercury, lead, thallium, and other toxic compounds, is mixed with water and stored in ponds. If not properly managed, the ponds can leach contaminants into the groundwater. Moreover, ash spills have resulted in major environmental and economic damage. In 2014, nearly 40,000 tons of coal ash spilled into the Dan River in North Carolina. The cleanup was estimated to be $300 million. To reduce these types of accidents, the EPA finalized regulations on the disposal and management of coal ash in 2016.