Water is vital to life, which is part of why we study what’s in it.
What comes out of our tap isn’t just molecules of H₂O — over 15 septillion of them in a standard glass of water. There also are natural minerals, dissolved organic and biological matter, along with substances that enter from agriculture, industry, consumer products and treatment processes.
Most of these substances are harmless at the concentrations typically found in water. Some are beneficial, and even essential, like sodium, fluoride and calcium ions that build strong bones and teeth, and help balance electrolytes that regulate heart function.
In fact, drinking large quantities of completely demineralized water can disrupt the body’s electrolyte balance. To absorb and regulate it, your body would reduce sodium levels in the blood, risking hyponatremia — a potentially life-threatening condition with such symptoms as nausea, muscle cramps, hallucinations and seizures.
But other waterborne chemicals are dangerous.
Most people encounter water-quality science through an annual report from their local water company. It’s usually a couple of pages long, with chemical names and numbers in a table. It lists various types of chemicals or compounds, summarizes what has been found in tests of wells, rivers and reservoirs, and explains whether the water meets government standards that promote and protect public health.
These reports provide important information about drinking water safety, but they are not a complete inventory of every substance scientists can detect or are working to understand.
We study a range of contaminants found in drinking water, with the goal of developing technologies to further safeguard public health. This can include pollutants and pathogens not included in an annual report.
A world of sneaky water pollutants
Consider per- and polyfluorinated substances, more commonly known as PFAS, and also called “forever chemicals” because they persist in the environment for a long time. These are a large family of chemicals used in consumer products expressly because they resist water, oil and stains.
Research has linked exposure to certain PFAS with adverse chronic health effects, such as endocrine disruption, low birth weight in fetuses and even certain types of cancer.
Federal drinking water standards now limit the amount of the two most common types of PFAS found in drinking water to 4 parts per trillion — the equivalent of four drops of water in 20 Olympic-size swimming pools. However, the broader chemical family includes many other substances whose occurrence and health effects are less understood by scientists and completely missed by the public or policy.
The challenge water-quality engineers face is not simply to determine whether PFAS or other compounds and pollutants are present. Researchers need to understand their concentrations in the water, how people are exposed to them, what their effects are, and how effectively different treatment technologies can remove or destroy them. There are many emerging technologies to combat these chemicals. Promising approaches may involve heating and pressurizing water.
Residue from pharmaceuticals that pass through people’s bodies enters sewage systems. Agricultural pesticides flow off croplands into waterways. Both of these types of waste can break down into new, less-studied compounds as they move through soil and water, eventually collecting in groundwater or wastewater to be treated and redistributed. Their potential long-term effects are not yet known.
Water treatment plants often use chlorine as part of the purification process. But when chlorine encounters natural organic matter, such as decayed plants and microorganisms, it forms disinfection by-products. These include chemicals such as trihalomethanes, which are known carcinogens that must be removed with further treatment before the water is safe to drink.
What doesn’t kill you … might later
We water-quality scientists want to know not only what’s in the water but also what it might do to your body right away — or across decades.
The timescale and route of exposure of waterborne contaminants matter. If undrained pipes are left unused for a long time, bacteria can build up. Then, when people run a shower or start an outdoor fountain, the bacteria that spray into the air pose a different kind of threat than exposure to a chemical pollutant in drinking water.
Take, for example, Legionella spp., a group of bacteria that can grow in drinking water distribution systems and power plant cooling towers when condensation pools. With a large buildup of the bacteria, people who inhale the water vapor can develop an acute form of pneumonia called Legionnaires’ disease.
Some contaminants pose an immediate threat; others pose threats that accumulate over time. For instance, ingesting microplastics in drinking water may not immediately hurt you, but they are being detected in people’s blood years after exposure. Some environmental labs are starting to offer direct-to-consumer microplastics water tests, though they can be costly.
Hazards, risks and Flint
Lead in a water pipe is a hazard, but as long as the water flowing through it is chemically stable and doesn’t cause the metal to leach from the pipes, the immediate risk to human health is low. In Flint, Michigan, in 2014, water from a new source was not chemically treated to reduce that threat. By 2016, residents had been ordered not to drink the water because it was contaminated with dangerous levels of lead, which can cause neurological problems and impair brain function, particularly in infants and children.
Key steps are determining whether your property has lead pipes and then, if it does, testing your water for the presence of lead.
The questions to always consider go beyond basic details of what’s in water, to include what kinds of dangers it might pose, whether immediate like Legionnaire’s disease or over time like lead poisoning. And federal regulatory standards don’t always address every potential source or type of contamination.
So the next time you review your local water report, don’t just look at what is being monitored: Think about what may not be on the list at all.
Sarah Glass and Madelyn Whitaker are PhD candidates in engineering at Rice University who are affiliated with the Rice Water Institute.
This article was produced in collaboration with The Conversation, a nonprofit news organization.
The post We study water quality. Here’s how we think about what comes out of the tap. appeared first on Washington Post.
