Billions of people around the world still lack access to safe drinking water, basic toilets and good hygiene. For children – more susceptible to infectious disease than adults – the consequences can be fatal.
Hundreds of children under the age of 5 die every day from diarrhoeal diseases that could have been prevented by basic WASH services in their homes, health centres and schools. Millions more find themselves missing out on essential nutrients or education – too often home sick from unsafe drinking water.
Children living in urban settlements and rural areas are more likely than others to be cut off from clean water and sanitation. So too are those growing up in places affected by climate change: From droughts to floods to heat waves, extreme weather events are making water sources less safe as they become more scarce.
During humanitarian emergencies, children already suffering life-threatening experiences are forced, also, to contend with waterborne risks. In fact, children living in conflict zones are almost 20 times more likely to die from diarrhoeal disease than from the violence itself.
Scientists estimate that bottled water drinkers swallow up to 90,000 more microplastic particles per year than those who stick to tap water.
Source:Concordia University
Summary:A chance encounter with plastic waste on a tropical beach sparked a deep investigation into what those fragments mean for human health. The research reveals that bottled water isn’t as pure as it seems—each sip may contain invisible microplastics that can slip through the body’s defenses and lodge in vital organs. These tiny pollutants are linked to inflammation, hormonal disruption, and even neurological damage, yet remain dangerously understudied.Share:
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Recent research has revealed that people may be unknowingly ingesting tens of thousands of microplastic particles every year. On average, individuals consume between 39,000 and 52,000 particles annually, with bottled water drinkers taking in an additional 90,000 microplastic fragments compared to those who drink tap water. Credit: Shutterstock
Thailand’s Phi Phi Islands are known for their crystal-clear waters and white sand, not for launching advanced scientific research. Yet for one environmental scientist, the contrast between natural beauty and pollution sparked a major career shift from business to environmental science.
“I was standing there looking out at this gorgeous view of the Andaman Sea, and then I looked down and beneath my feet were all these pieces of plastic, most of them water bottles,” she says.
“I’ve always had a passion for waste reduction, but I realized that this was a problem with consumption.”
Armed with years of experience as co-founder of ERA Environmental Management Solutions, a company specializing in environmental, health and safety software, she returned to Concordia University to pursue a PhD on plastic waste. Her recent paper in the Journal of Hazardous Materials explores how single-use plastic water bottles pose potential health risks that remain largely overlooked in scientific research.
Hidden Hazards of Bottled Water
In an extensive review of more than 140 studies, the research reveals that people consume between 39,000 and 52,000 microplastic particles every year, and those who drink bottled water take in roughly 90,000 more than tap water users.
These microplastics are tiny fragments, often invisible to the eye. A typical particle measures between one micron (a thousandth of a millimeter) and five millimeters, while nanoplastics are even smaller. The contamination begins during manufacturing, transportation, and storage, when low-quality plastics release microscopic fragments — especially when exposed to sunlight and fluctuating temperatures. Unlike microplastics from food sources, those in bottled water are ingested directly.
Inside the Human Body
Once consumed, these particles can travel throughout the body. Studies indicate that microplastics can cross biological barriers, enter the bloodstream, and accumulate in organs. This may cause chronic inflammation, oxidative stress, hormonal disruption, reproductive impairment, neurological issues, and even some cancers. However, the long-term impact remains uncertain due to limited standardized testing and measurement techniques.
The researcher highlights that current detection tools vary in precision and capability. Some methods can spot smaller particles but cannot identify their composition, while others analyze chemical makeup but miss the tiniest plastics. The most advanced systems are both expensive and difficult to access, hindering consistent global study.
Rethinking Plastic Use Through Education
Despite growing environmental laws aimed at reducing plastic pollution, most regulations target items like shopping bags, straws, and packaging. Single-use water bottles often escape similar scrutiny.
“Education is the most important action we can take,” she says. “Drinking water from plastic bottles is fine in an emergency but it is not something that should be used in daily life. People need to understand that the issue is not acute toxicity — it is chronic toxicity.”
Chunjiang An, associate professor, and Zhi Chen, professor, in the Department of Building, Civil and Environmental Engineering at the Gina Cody School of Engineering and Computer Science contributed to this paper.
This research was supported by the Natural Sciences and Engineering Research Council of Canada and Concordia University.
Background: Warming caused by climate change can impact human health risks associated with drinking water. This review aimed to synthesize the evidence about the effects of increasing temperatures in the drinking water distribution system (DWDS) on health-related chemical and microbial water quality parameters. We also identified adaptation options. Methods: We conducted a scoping review of quantitative peer-reviewed studies published up to March 2023, and research reports published up to April 2024, specifically looking at a DWDS or comparable experimental conditions. Results: We included 28 studies in this review. Evidence focused on chlorinated systems in higher-income countries. Warming has variable effects on microbial communities within the DWDS. Accumulation and release of heavy metals may increase at higher temperatures, depending on pipe materials. Warming also speeds up the decay of chlorine and chloramine, affecting the formation of disinfectant byproducts and the potential of microbial (re)growth. Multiple effects can occur simultaneously, requiring an integrated adaptation approach. Technical and institutional adaptation options, such as improved removal of dissolved organic carbon during treatment covering the entire DWDS were identified. Discussion: With increasing climate change, the identified effects can become more prominent without adaptation. However, no included studies quantified how these effects would translate into human health impacts.
Populations worldwide are exposed to a myriad of chemicals via drinking water, yet only a handful of chemicals have been extensively evaluated with regard to human exposures and health impacts [1, 2]. Many chemicals are generally “invisible” in that they do not alter the color or odor of drinking water, and many of the associated effects are not observable for decades, making linkages between exposure and disease difficult. The articles included in the Journal of Exposure Science and Environmental Epidemiology Special Topic “Assessing Exposure and Health Consequences of Chemicals in Drinking Water in the 21st Century” cover a range of topics, including: (i) new exposure and health research for regulated and emerging chemicals, (ii) new methods and tools for assessing exposure to drinking water contaminants, (iii) issues of equity and environmental justice, (iv) drinking water issues within the context of a changing climate. This Special Topic includes articles authored by experts across multiple disciplines including environmental engineering, hydrology, exposure science, epidemiology, toxicology, climate science, and others. Many of these papers emerged from an international symposium organized by ISGlobal and Yale scientists held in Barcelona in September 2022 [3].
Regulated chemicals
Chemicals that have been the focus of environmental health research include disinfection by-products (DBPs), nitrate, and metals. Although many of these chemicals are regulated, there is concern about low-dose exposures at concentrations below standards and guidelines, and risks of health endpoints not yet studied. Kaufman et al. explore new ways to assess DBP exposure, considering concentrations and specific toxicity potential in relation to birth defects risk [4]. Long-term exposure to DBPs and nitrate is addressed by Donat-Vargas et al. in relation to chronic lymphocytic leukaemia in Spain [5]. Friedman et al. examine temporal and spatial variability of manganese concentrations in a case study in the United States (US) [6]. Hefferon et al. evaluated sociodemographic inequalities in fluoride concentrations across the US [7]. Spaur et al. evaluate the contribution of water arsenic to biomarker levels in a prospective study in the US [8].
Chemicals of emerging concern
Many emerging chemicals, such as per- and polyfluoroalkyl substances (PFAS), microplastics, and 1,4-dioxane, have drinking water as the dominant exposure pathway for many populations. Yet, these remain largely unregulated or have standards and guidelines that vary widely across states and countries. Because only small percentages of the universe of contaminants are regulated in drinking water, routine monitoring data for many chemicals of emerging concern is frequently absent or very limited. To advance understanding of drinking water exposures to PFAS, Cserbik et al. [9]. and Kotlarz et al. [10]. evaluate and compare PFAS in drinking water and blood serum samples in two different settings: an urban setting not impacted by PFAS pollution in Spain [9] and among well water users living near a fluorochemical facility in the US [10], respectively.
New methods and tools for exposure assessment
There is a need for improved tools, methods, and data to evaluate drinking water related exposures. These tools and techniques remain somewhat limited and lag behind those of other stressors (e.g., air pollution). Also, despite water contaminants occurring in mixtures, most of the evaluations (and policies and regulations) are conducted chemical by chemical, ignoring potential interactions. Schullehner et al. present case studies of three approaches of exposure assessment of drinking water quality: use of country-wide routine monitoring databases, wide-scope chemical analysis, and effect-based bioassay methods [11]. Luben et al. elaborate and compare different exposure assessment metrics to trihalomethanes in epidemiological analyses of reproductive and developmental outcomes [12]. Escher et al. present in vitro assays to evaluate biological responses of including neurotoxicity, oxidative stress, and cytotoxicity in different types of drinking water samples (tap, bottled, filtered) [13] Isaacs et al. present newly developed automated workflows to screen contaminants of concern based on toxicity and exposure potential [14]. Dorevitch et al. develop a novel method to improve detection of particulate lead spikes [15].
Issues of equity, environmental justice, and vulnerable populations
A substantial portion of the population (e.g., 20% in the United States) have private water supplies (e.g., a household domestic drinking water well), which are not subject to any federal regulatory oversight or monitoring [16]. This presents an equity issue in access to data on drinking water quality, as discussed in Levin et al. [2]. and heterogeneity in state-based policies for drinking water prevention, as discussed by Schmitt et al. [17]. Spaur et al. [8], observed that water from unregulated private wells and regulated municipal water supplies contributes substantially to overall exposures (as measured by urinary arsenic and uranium concentrations) in both rural, American Indian populations and urban, racially/ethnically diverse populations nationwide. Hefferon et al. evaluated environmental justice issues with respect to fluoride and found that 2.9 million US residents are served by public water systems with average fluoride concentrations exceeding the World Health Organization’s guidance limit [7]. Friedman et al. show that manganese in drinking water frequently exceeds current guidelines in the US, and occur at concentrations shown to be associated with adverse health outcomes, especially for vulnerable and susceptible populations like children [6].
Chemical contamination may also pose a serious threat in the developing world. Today, around 2.2 billion people – or 1 in 4 – still lack safely managed drinking water at home [18]. In most of the world, microbial contamination is the biggest challenge. Because it has been understudied, the chemical risks remain obscure [19], and regulators often require local data to take action. Praveena et al. reviews the quality of different drinking water types in Malaysia (tap water, ground water, gravity feed system) and its implications on policy, human health, management, and future research [20].
Water quality in a changing climate
There is an urgent need to anticipate and prepare for current and future challenges in a rapidly changing world. We also need to foresee new challenges to address issues of water scarcity (e.g., increasing desalination, use of treated wastewater in densely populated urban areas to meet water use demands), and aging infrastructure for many middle- and high-income countries constructed in the nineteenth and twentieth centuries. The impacts of climate change on the water cycle are direct and observable, such as more frequent droughts and floods, sea level rise, and ice/snow melt. These events will challenge drinking water quality and availability through direct and indirect mechanisms [21]. There is still very limited knowledge on how climate events will affect the quality of finished drinking water. In our special issue, Oliveras et al. conducts a new analysis on the impacts of drought and heavy rain surrogates on the quality of drinking water in Barcelona, Spain [22].
Conclusion
Chemical contamination of drinking water is widespread. Although our knowledge on chemical risks in drinking water is increasing, there are knowledge gaps that make a slow translation to public health protection. We hope this issue highlights, elevates, and motivates research on chemical exposures via drinking water.
Atide of anger is rising in New Zealand’s capital, Wellington, as the city’s toilets continue to flush directly into the ocean more than two weeks after the catastrophic collapse of its wastewater treatment plant.
Millions of litres of raw and partially screened sewage have been pouring into pristine reefs and a marine reserve along the south coast daily since 4 February, prompting a national inquiry, as the authorities struggle to get the decimated plant operational.
Abandoned beaches, public health warning signs and seagulls eating human waste are now features of the popular coastline, with the environmental disaster zone adjacent to the airport where thousands of international visitors alight every day.
Fears for the safety of marine ecosystems – including vulnerable species such as the little blue penguin, or kororā, which nest along the shore – are mixed with concerns over the length and cost of disruption to those who depend on the coast for income, wellness, and recreation.
As a southerly storm whipped through the lower North Island and churned up polluted seawater this week, hundreds of residents turned out to a public meeting to seek answers.
“They’re warning us to close our windows because a shit-laden hurricane is coming at us,” said the south coast resident and environmentalist Eugene Doyle, whose house faces the sea. “Everyone in charge has done an appalling job, and they need to be held accountable.”
Ray Ahipene-Mercer with a bottle of treated water. Photograph: Hagen Hopkins
Ray Ahipene-Mercer, 78, who led a 16-year campaign to get the treatment plant built throughout the 80s, said he felt gutted. Before 1998, the ocean smelled and looked terrible, with visible excrement on the rocks and surfers routinely emerging with ear infections and gastroenteritis.
“I thought it was all done, and here we are back to where we were 30 years ago,” Ahipene-Mercer, of Ngāi Tara descent, said. “It’s a catastrophe.”
On 4 February, an overnight electrical failure flooded the Moa Point wastewater treatment plant, destroying 80% of the equipment. Initially, raw sewage was being pumped directly out of a five-metre pipe near a beach at Tarakena Bay. Now, most sewage is being sent 1.8km offshore in the Cook Strait, after being screened for large objects such as tampons and wet wipes.
Water management has long been a contentious issue in New Zealand, with legislation to centralise its control and overhaul outdated services thrown out by the National-led coalition government in favour of local reforms in early 2024.
In Wellington, ageing pipes have caused issues with wastewater and stormwater flooding. The Moa Point plant is owned and overseen by two layers of local government and a council-owned water utility – Wellington Water – who contract the French-owned waste management company Veolia to run the plant.
A general view of Moa Point Wastewater Plant, Wellington Airport and Lyall Bay. Photograph: Hagen Hopkins
“It looked convoluted to me, and it wasn’t clear where actual authority lay,” the Wellington mayor, Andrew Little, who has been in the job four months, told the Guardian, adding that Wellingtonians were in a “state of shock”.
A crown inquiry called by the local government minister, Simon Watts, will look into the causes of the disaster. “The public is owed the assurance that we understand what led to this failure and that we are taking steps to prevent it from happening again,” Watts told Radio New Zealand.
He said that as part of the coalition government’s water reforms, a new entity, Tiaki Wai, would take over from Wellington Water in July, which he expected to improve services. Councils were responsible for underinvesting in water infrastructure, and new legislation would address this, he said.
Little said he could not speculate on the causes due to the inquiry. Wellington Water did not respond to specific questions by deadline, and has said it could not comment publicly due to the ongoing inquiry. Veolia also declined to comment.
Wellington Water chair Pat Dougherty previously told Radio New Zealand there had been underinvestment over a long period at Moa Point, and he backed an investigation. “I worry that there may have been some early warning signs that there were troubles with the discharge and we missed those. But everything needs to be on the table.”
But for many, this is cold comfort. Locals say lower-level pollution has already marred the short Wellington summer, with recurring sewage discharges pointing to a deeper issue at the plant. Official reports showcontinuing issues and warnings about underfunding for years, and the authorities have said a fix could still be months away.
“We are looking at generations of negligence, at a time where our climate is changing dramatically,” said Tamatha Paul, the Green party MP for Wellington Central and former city councillor who called this week’s meeting.
Pedestrians walk past a warning sign between Island Bay and Owhiro Bay. Photograph: Hagen Hopkins
“The way this will affect really vulnerable, delicate species that are already endangered, the fact their entire habitat is being devastated is heartbreaking.”
Central government help is crucial, she said.
Local iwi [tribes] have long opposed any wastewater going into the ocean, Taranaki Whanui chair Te Whatanui Winiata said. “This is our source of sustenance, we are relations to the moana [ocean]. We have been crying about this from the start, saying this kind of sewage system just causes havoc. The response from our people is outrage, shock, and anguish.”
As beaches remain closed and businesses report losses, the Victoria University marine biologist Christopher Cornwall said “huge numbers” of marine creatures who call the various reefs around the south coast home would be suffering the most.
Continued pollution could cause a mass kelp die-off in the Taputeranga Marine Reserve – home to species such as mussels, kina, pāua, sea sponges, fish, crayfish, octopus and penguins – killing their homes and food sources, he said.
The Green MP Tamatha Paul. Photograph: Hagen Hopkins
Human-borne bacteria and viruses could make these sea creatures sick, along with accumulating in shellfish, making them unsafe to eat. Microplastics get into the stomachs of seabirds and penguins who eat human waste, making them think they are full so that they die of starvation.
The Department of Conservation has said the extent of the damage is not yet known, but would be affected by the length and volume of discharge, ocean currents and wind.
New Zealanders needed to rethink why wastewater was going into oceans in the first place, Cornwall said. “I have no idea why you’d put a pipe in between two reefs anyway, and now all those fecal materials are just getting swept right in. Why are we pumping sewage out on to a kelp forest? It’s clearly not OK, and we should never have been in this situation.”
It’s a feeling shared by many. From her home in Island Bay, Kayla Henderson often watches dolphins playing in Taputeranga reserve. Outside the meeting this week, the young ocean lover felt helpless.
“I just care about the environment,” she said. “And I want to have faith that we won’t have raw sewage and rubbish going into protected marine waterways. I didn’t think it would be that hard.”
Background: Humans are primary drivers of environmental-contaminant exposures worldwide, including in drinking-water (DW). In the United States, point-of-use DW (POU-DW) is supplied via private tapwater (TW), public-supply TW, and bottled water (BW). Differences in management, monitoring, and messaging and lack of directly-intercomparable exposure data influence the actual and perceived quality and safety of different DW supplies and directly impact consumer decision-making.
Low confidence in water quality is associated with perceptions of public corruption
Source:Northwestern University
Summary:A new study finds more than half of adults surveyed worldwide expect to be seriously harmed by their water within the next two years. The study sought to understand public perceptions of drinking water safety. Because perceptions shape attitudes and behaviors, distrust in water quality has a negative impact on people’s health, nutrition, psychological and economic well-being — even when the water meets safety standards.Share:
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A new study finds more than half of adults surveyed worldwide expect to be seriously harmed by their water within the next two years. Led by global health experts at Northwestern University and the University of North Carolina at Chapel Hill, the study sought to understand public perceptions of drinking water safety.
Because perceptions shape attitudes and behaviors, distrust in water quality has a negative impact on people’s health, nutrition, psychological and economic well-being — even when the water meets safety standards.
“If we think our water is unsafe, we will avoid using it,” said Sera Young, professor of anthropology and global health at Northwestern and senior author of the new study.
“When we mistrust our tap water, we buy packaged water, which is wildly expensive and hard on the environment; drink soda or other sugar-sweetened beverages, which is hard on the teeth and the waistline; and consume highly processed prepared foods or go to restaurants to avoid cooking at home, which is less healthy and more expensive,” Young said. “Individuals exposed to unsafe water also experience greater psychological stress and are at greater risk of depression.”
Young is a Morton O. Schapiro Faculty Fellow at the Institute for Policy Research, a faculty fellow at the Paula M. Trienens Institute for Sustainability and Energy, and co-lead of the Making Water Insecurity Visible Working Group at the Buffett Institute for Global Affairs.
Using nationally representative data from 148,585 adults in 141 countries from the 2019 Lloyd’s Register Foundation World Risk Poll, the authors found a high prevalence of anticipated harm from water supply, with the highest in Zambia, the lowest in Singapore and an overall mean of 52.3%.
They also identified key characteristics of those who thought they would be harmed by their drinking water. Women, city dwellers, individuals with more education, and those struggling on their current income were more likely to anticipate being harmed by their drinking water.
The researchers found that, surprisingly, higher corruption perception index scores were the strongest predictor of anticipated harm from drinking water, more so than factors like infrastructure and Gross Domestic Product.
Further, even within countries with consistent access to basic drinking water services, doubts about the safety of water were widespread. This includes the U.S. where 39% of those polled anticipated serious harm from drinking water in the short term.
“Our research highlights that it is imperative both to deliver safe drinking water and to make sure that people have confidence in their water source,” said Joshua Miller, a doctoral student at the UNC Gillings School of Global Public Health and the study’s first author.
The researchers note that it is difficult for consumers to judge the hazards and safety of their water supply because many contaminants are invisible, odorless and tasteless. Without adequate information, many are left to evaluate the safety of their water based on prior experiences, media reports, and personal values and beliefs.
“It’s also possible that people correctly judge the safety of their water,” Young said. “The good people of Flint didn’t trust their water and they were spot on.”
The co-authors suggest actions officials can take to improve public trust around drinking water, including efforts to make testing more readily available, translate test results, replace lead pipes and provide at-home water filters when contaminants are detected, as well as provide improved access to safe drinking water.
“This is the kind of work that can catalyze greater attention and political will to prioritize these services in national development plans and strategies, and get us closer to achieving universal access to safe drinking water,” said Aaron Salzberg, director of the Water Institute at the UNC Gillings School of Global Public Health.
Salzberg previously served as the special coordinator for water resources in the U.S. Department of State, where he was responsible for managing the development and implementation of U.S. foreign policy on drinking water and sanitation, water resources management and transboundary water issues.
Drinking water contaminated with Pfas chemicals probably increases the risk of infant mortality and other harm to newborns, a new peer-reviewed study of 11,000 births in New Hampshire finds.
The first-of-its-kind University of Arizona research found drinking well water down gradient from a Pfas-contaminated site was tied to an increase in infant mortality of 191%, pre-term birth of 20%, and low-weight birth of 43%.
It was also tied to an increase in extremely premature birth and extremely low-weight birth by 168% and 180%, respectively.
The findings caught authors by surprise, said Derek Lemoine, a study co-author and economics professor at the University of Arizona who focuses on environmental policymaking and pricing climate risks.
“I don’t know if we expected to find effects this big and this detectable, especially given that there isn’t that much infant mortality, and there aren’t that many extremely low weight or pre-term births,” Lemoine said. “But it was there in the data.”
The study also weighed the cost of societal harms in drinking contaminated water against up-front cleanup costs, and found it to be much cheaper to address Pfas water pollution.
Extrapolating the findings to the entire US population, the authors estimate a nearly $8bn negative annual economic impact just in increased healthcare costs and lost productivity. The cost of complying with current regulations for removing Pfas in drinking water is estimated at about $3.8bn.
“We are trying to put numbers on this and that’s important because when you want to clean up and regulate Pfas, there’s a real cost to it,” Lemoine said.
Pfas are a class of at least 16,000 compounds often used to help products resist water, stains and heat. They are called “forever chemicals” because they do not naturally break down and accumulate in the environment, and they are linked to serious health problems such as cancer, kidney disease, liver problems, immune disorders and birth defects.
Pfas are widely used across the economy, and industrial sites that utilize them in high volume often pollute groundwater. Military bases and airports are among major sources of Pfas pollution because the chemicals are used in firefighting foam. The federal government estimated that about 95 million people across the country drink contaminated water from public or private wells.
Among those are toxicological studies in which researchers examine the chemicals’ impact on lab animals, but that leaves some question about whether humans experience the same harms, Lemoine said.
Other studies are correlative and look at the levels of Pfas in umbilical cord blood or in newborns in relation to levels of disease. Lemoine said those findings are not always conclusive, in part because many variables can contribute to reproductive harm.
The new natural study is unique because it gets close to “isolating the effect of the Pfas itself, and not anything around it”, Lemoine said.
Researchers achieved this by identifying 41 New Hampshire sites contaminated with Pfoa and Pfos, two common Pfas compounds, then using topography data to determine groundwater flow direction. The authors then examined reproductive outcomes among residents down gradient from the sites.
Researchers chose New Hampshire because it is the only state where Pfas and reproductive data is available, Lemoine said. Well locations are confidential, so mothers were unaware of whether their water source was down gradient from a Pfas-contaminated site. That created a randomization that allows for causal inference, the authors noted.
The study’s methodology is rigorous and unique, and underscores “that Pfas is no joke, and is toxic at very low concentrations”, said Sydney Evans, a senior science analyst with the Environmental Working Group non-profit. The group studies Pfas exposures and advocates for tighter regulations.
The study is in part effective because mothers did not know whether they were exposed, which created the randomization, Evans said, but she noted that the state has the information. The findings raise questions about whether the state should be doing a similar analysis and alerting mothers who are at risk, Evans said.
Lemoine said the study had some limitations, including that authors don’t know the mothers’ exact exposure levels to Pfas, nor does the research account for other contaminants that may be in the water. But he added that the findings still give a strong picture of the chemicals’ effects.
Granular activated carbon or reverse osmosis systems can be used by water treatment plants and consumers at home to remove many kinds of Pfas, and those systems also remove other contaminants.
The Biden administration last year put in place limits in drinking water for six types of Pfas, and gave water utilities several years to install systems.
The Trump administration is moving to undo the limits for some compounds. That would probably cost the public more in the long run. Utility customers pay the cost of removing Pfas, but the public “also pays the cost of drinking contaminated water, which is bigger”, Lemoine said.
Researchers tested spring, groundwater, and purified bottled waters against local tap to see how treatment shapes the byproducts that emerge — and the differences were striking.
A new study found that bottled water contains lower levels of disinfection byproducts (DBPs) than chloraminated tap water, averaging less than half the amount found in typical U.S. tap samples.
Researchers detected DBPs—including trihalomethanes and haloacetic acids—in all 10 bottled water brands tested, though levels remained relatively low.
Spring and groundwater brands tended to have fewer DBPs than purified bottled waters, making them the better choice for minimizing chemical byproducts.
The news hasn’t been great for bottled water fans lately. In January, Food & Wine reported on a new study showing that the more bottled water you drink, the more microplastics you consume, and another study showing that bottled water may contain more bacteria than you might expect. And don’t even get us started on what happens when you leave bottled water in a hot car for too long.
Now, a new study published in the journal Water Research is giving bottled water the silver lining it desperately needs.
In the new March issue, researchers from the University of South Carolina published findings measuring levels of disinfection byproducts (DBPs) in bottled water compared to chloraminated tap water. The study noted that bottled water often begins as municipal tap water, which is sometimes further disinfected. This process, the researchers added, can form DBPs, chemical compounds created when disinfectants react with natural organic matter.
The researchers noted that some of these DBPs are already regulated in bottled water by the U.S. Food and Drug Administration (FDA); however, many more fly under the unregulated radar. To find out which ones may be lurking in your water, the researchers purchased 10 popular brands of bottled water from local stores, including lower-cost “grocery” brands, mid-tier “name” brands, and higher-end “designer” brands. Some of the water was labeled as “purified” (often just code for treated tap water), while others were labeled as spring or groundwater. They also collected a sample of local tap water (treated with chloramine) for comparison with the bottled brands.
The researchers then tested for 64 different DBPs, including 50 unregulated DBPs that had not previously been measured in bottled water. They found that every bottled water sample they tested contained some level of disinfection byproducts, but at relatively low levels, ranging from 0.01 to 22.4 micrograms per liter, or up to about 22 millionths of a gram in roughly 34 ounces of water. By comparison, the tap water sample they analyzed contained 47.3 micrograms per liter, and previous studies suggest U.S. tap water averages closer to 52 micrograms per liter, about double the highest bottled water level measured in this study.
Bottled water vs. tap water: How do DBP levels compare?
Water Type
DBP Levels in This Study
How It’s Treated
What to Know
Purified bottled water
0.01–22.4 µg/L (some samples near the higher end of the bottled range)
Often municipal tap water that has been further treated (e.g., reverse osmosis, distillation, or carbon filtration)
May still contain DBPs formed during disinfection. Levels varied by lot.
Spring/groundwater bottled water
Generally lower overall DBPs than purified brands
Sourced from underground aquifers; may be disinfected but often undergoes less treatment than purified water
Showed lower DBP levels in this study, but not DBP-free.
Chloraminated tap water (sample)
47.3 µg/L
Treated with chloramine to kill pathogens
Higher DBPs than any bottled sample tested, but within federal regulatory limits.
Average U.S. tap water (prior research)
~52 µg/L
Typically chlorinated or chloraminated
Federal EPA limit for total trihalomethanes is 80 µg/L.
Here’s how disinfection byproduct (DBP) levels in bottled water brands stack up against chloraminated tap water samples and prior U.S. averages.
And a hot tip: If you’re hoping to score the bottled water with the lowest levels of DBPs, go for spring and groundwater, which showed lower overall DBPs than purified brands.
As for which byproducts they identified, the team reported that trihalomethanes and haloacetic acids had the highest concentrations. Both are common DBPs that form when chlorine reacts with organic matter in water. (However, some studies have linked long-term exposure at high levels to an increased risk of certain cancers.) The researchers also found several unregulated DBPs, including dibromoacetonitrile, which is carcinogenic.
The one thing the team couldn’t do was say with certainty that there is a “safest” brand of water, because DBP levels varied from lot to lot, making brand-level comparisons impossible. As for what’s next, the team hopes their work can inform future studies tracking these DBPs over time to see how they develop as water sits on the shelf.
Bottom line: Bottled water isn’t DBP-free — but it may contain lower levels than some tap water. If you’re concerned, spring water and proper storage are your best bets. And as always, balance convenience, cost, and environmental impact before stocking up.
Weng, Weizhe, Andrea Albertin, and Yilin Zhuang. 2024. “From Wells to Wellness: An Introduction to Drinking Water Systems in Florida: FE1156, 10 2024”. EDIS 2024 (5). Gainesville, FL. https://doi.org/10.32473/edis-fe1156-2024.
Abstract
Safe drinking water is a fundamental requirement for human health and well-being. This publication is part of an EDIS series that aims to illuminate the critical issues surrounding drinking water quality and Florida’s drinking water system. In this article, we begin with a brief introduction to the different categories of Florida’s drinking water system. Then, we discuss relevant federal and state level regulations for each category. Information sources and channels are provided for readers to access drinking water information in their communities. The content is designed to benefit a diverse audience, including researchers, communications and outreach experts, environmental professionals, healthcare providers, and policymakers. It seeks to clarify the facts and regulatory framework governing drinking water systems, identify areas that require targeted extension programs, and aid in the development of outreach materials to ensure the provision of safe drinking water.
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