Our paper was including the Nature Geoscience Focused issue on “Inland waters under threat”

ature Geoscience has just been published and features a bunch of great papers and opinion pieces about inland aquatic systems. We’ve taken the opportunity to put together a special focus collection on inland waters, their many contributions to ecosystems and biogeochemical cycles, and the challenges they face due to climate change and human actions.

High levels of endocrine pollutants in US streams during low flow due to insufficient wastewater dilution

Cool YouTube Videos developed by our students

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Nanosystems Engineering Research Center (NEWT)

Videos created by members of the NSF funded Nanotechnology-Enabled Water Treatment (NEWT) Engineering Research Center – a collaboration between Rice University, Arizona State University, Yale University, and the University of Texas El Paso.

notechnology limit biofouling in water treatment?

How silver nanoparticles can help reduce biofouling in water filters

How silver nanoparticles can help reduce biofouling in water filters

How silver nanoparticles can help reduce biofouling in water filters

How silver nanoparticles can help reduce biofouling in water filters?




Portrait of Paul Westerhoff with a caption of His ideas are transformational . . . and he's never satisfied with small, incremental advances in knowledge,” says a colleague of new ASU Regent’s Professor Paul Westerhoff. “Because of his persistence and dedication, Paul's work will always be on the cutting edge." Photographer: Jessica Hochreiter.

Paul Westerhoff figures he was “destined to be an engineer.” But that is mostly because while growing up, he jokes, “I just didn’t know anything else existed.”

His father was an environmental engineer. One of his two older brothers became an electrical engineer, the other a mechanical engineer. It just seemed natural for him to follow in the family footsteps.

Still, Westerhoff took his time in college before declaring a major. The only thing he was decided on was that “I wanted to do work involved with things outside.”

He liked the outdoors and gravitated toward “doing things around water,” specifically lakes, streams and rivers.

It was a course in hydrology — the study of water in the environment —that finally fixed him onto a specific educational track.

“It was the first time I had a class that really integrated my interests in mathematics, statistics and technology, and the teacher talked about how all that could relate to rivers,” Westerhoff recalls. “Everything just came together for me at that point.”


The water thing has worked out well for him. Westerhoff, a professor of civil, environmental and sustainable engineering in Arizona State University’s Ira A. Fulton Schools of Engineering, is today a well-recognized leader in water treatment and water safety research.

He has received many of the most highly regarded awards for his work in the field, and his more than 200 peer-reviewed journal publications have made him among the most highly cited researchers in environment and ecology studies.

He directs a U.S. Environmental Protection Agency research network that teams nine universities to study the lifecycles of nanomaterials and their impacts on the environment and human health.

He is deputy director of the National Science Foundation Engineering Research Center on Nanotechnology Enabled Water Treatment. The center is developing technologies to provide clean water to millions of people in areas throughout the United States that still lack it.


During his 22 years at ASU, he has also received accolades for his skills as a teacher, mentor and administrator.

Westerhoff has garnered awards for his work mentoring doctoral students and teaching undergraduates, and has been instrumental in helping to establish the Fulton Schools’ graduate and undergraduate degree programs in environmental engineering.

He has also served at various times as a civil and environmental department chair, the founding director of the School of Sustainable Engineering and the Built Environment, the Fulton Schools Associate Dean for Research, the ASU Vice Provost for Academic Research Programming, and Senior Advisor on Science and Engineering to the ASU Provost.

In 2016 the Fulton Schools created a new position and he was named the interim Vice Dean of Research and Innovation.

Why take on the extra administrative tasks on top of his research and teaching?

“I just get bored,” he says,” “and I need to be intellectually challenged.”


With or without boredom as motivation, Westerhoff’s range of achievements has now earned him designation as a Regents’ Professor, the highest honor bestowed on faculty members at Arizona’s three state universities.

The title recognizes accomplishments in research, education, scholarship, creative endeavors and public service that have brought national and international distinction.

Colleagues attest to the widespread impact of Westerhoff’s contributions.

“His research is highly relevant to society because insufficient access to clean water is a major limiting factor to human capacity,” says Pedro J. Alvarez, the George R. Brown Professor of Civil and Environmental Engineering at Rice University and director of the Nanotechnology Enabled Water Treatment research center.

“Paul excels in scientific rigor. He does a great job of bridging the interface between the discovery-driven culture of science and the innovation-driven culture of engineering,” Alvarez adds. “It’s rare to find someone with such depth and breadth in issues related to water treatment.”

Menachem Elimelech, the Roberto Goizueta Professor at Yale University, points in particular to Westerhoff’s essential work exploring the environmental implications and applications of engineering nanomaterials as only one of his “numerous important contributions to the field of environmental engineering.”

University of Colorado Boulder Professor of Environmental Engineering R. Scott Summers sums up, “There are only a few who are able to visualize solutions to major challenges, and fewer still who can clearly articulate those solutions. Paul has that gift.”

“Paul’s research is never ordinary,” says Clemson University’s Vice President of Research Tanju Karanfil. “He’s always looking for solutions to environmental problems that are out of the box, and he’s never satisfied with small, incremental advances in knowledge. His ideas are transformational, which is exactly what our field needs. Because of his persistence and dedication, Paul’s work will always be on the cutting edge.”


Westerhoff doesn’t view his new Regents’ Professor status as a platform for shining a spotlight on career success. He hopes only that it might in some way boost his ability to make further impacts in the professional endeavors he cares about most.

In his new vice dean position, he wants to foster a stronger innovation mindset among the Fulton Schools’ 300-plus tenure-track faculty.

That involves them zeroing in more directly on use-inspired research pursuits with entrepreneurial potential.

“It’s the idea that progress isn’t just publishing in research journals, but in getting patents or starting a company,” he explains. “That might mean focusing on producing results that could have important concrete benefits rather than just finding out more about something that is merely interesting.”

“Paul is very creative and has a tremendous skill for identifying timely, relevant and interesting challenges,” says Julie Beth Zimmerman, an associate professor of chemical and environmental engineering at Yale University. “Not only is he adept at getting others to join the cause, he has a powerful gift in bringing out the best in those individuals, and even more importantly, realizing outcomes greater than the sum of the individual collaborators.”

Westerhoff is leading by example on the entrepreneurship front. He and his wife, Kelly, also an engineer (they met in graduate school), are forming a start-up that would license some of the water-treatment technologies he has developed and move them toward commercialization.

“I am manager and technical advisor,” he says. “She is the company president.”


He also wants to continue using his expertise to help communities through his work as a member of an EPA science advisory board, as well as with the information and advice he has been providing to local governments and public groups that have been regularly seeking his consultation for more than a decade.

He has been participating in efforts to find water treatment, safety and pollution solutions for a number of sizable municipalities and urban regions, including Los Angeles, as well as for rural agricultural and ranching areas.

“It’s really interesting to help bring science and engineering experience into the mix of making public policy, and to see it come together toward something positive,” he says.


With all of this multifaceted work on his agenda, Westerhoff still keeps teaching and mentorship high among his priorities.

He says one of best rewards of his job is watching the young undergraduates he teaches transition “from looking clueless and confused to starting to figure things out, to finally mastering complex concepts and ideas.”

With the advanced students, he likes pushing them to excel beyond the classroom — urging them to compete for scholarships, learn how to pitch themselves to employers, map out their career-planning strategies and develop their own research pursuits and their own creative approaches to problem solving.

Westerhoff’s measure of success in his role as an educator and research director is a simple one: “It’s when I’m learning as much from the students as they’re learning from me.”


ASU nanoparticle expert uses research to move society past fear

Read more

February 14, 2017

Newly named Regents’ Professor Paul Westerhoff is part of an initiative to harness the tiny specs to purify water

When people find out there are invisible particles in their food or water, they become alarmed.

Arizona State University professor Paul Westerhoff has dedicated his career to producing research that answers people’s questions and moves them past fear.

“The things I do are not from a scare-mongering point of view, but trying to answer objective engineering questions,” said Westerhoff, a professor of in the School of Sustainable Engineering and the Built Environment at ASU.

Westerhoff, an environmental engineer, has been named one of three Regents’ Professors for the 2016-2017 academic year. Regents’ Professor is the highest faculty honor and is conferred on full professors who have made remarkable achievements that have brought them national attention and international distinction.

An expert in nanoparticles, Westerhoff started working on the tiny specks even before they had a name. As a graduate student, he worked on water filtration.

“At that time we talked about these things called ‘sub-micron particles,’ which we couldn’t measure very well but we did a bunch of experiments with them anyway,” he said.

A few years later, when the term “nano” was becoming popular, he realized he had already done it.

“So I put in my first proposal, and it got funded because I was one of the first people who had data!”

Now, he focuses on using nanoparticles to treat and purify water, an interest that was piqued by a hydrology class he took as an undergraduate.

“I understand water,” he said. “I like fishing and swimming and kayaking, and I can go to a river and not only understand the hydrology. But I know why the water is a certain color. And I know where it came from. And I know all the fish that live in it.”

From his first studies, he saw the trajectory of public perception about invisible and unknown substances in the environment, and how that could influence his research.

“In the environmental world, initially it’s like the world’s going to end. But what I’ve learned is that these things move through predictable trends,” he said, using as an example “Silent Spring,” a 1962 book by conservationist Rachel Carson that documented the effects of the use of pesticides, including DDT.

“It’s in this early stage that people are scared, while the agriculture industry and pesticide industry responded by saying that they save millions of lives. In the first few years there’s a lot of uncertainty,” he said.

“Then researchers come along and help reduce that uncertainty.

“Then there’s another phase where politics come in, and there are cost decisions and people think about regulations and finding alternatives,” he said.

“We still find DDT in the environment, but it’s regulated and people really aren’t scared of it. It’s like a 20-year cycle.”

Westerhoff said the key is to know which phase is coming next.

“As a researcher you want to be focusing on what will be the important question to answer in three to five years, before people even know it’s a question,” he said.

“In nano, we were ahead of the game in thinking, ‘Maybe this isn’t so bad, maybe we can use it.’”

Now he’s deputy director of the Nanotechnology Enabled Water Treatment Systems Center, which is focused on developing compact, mobile, off-grid systems that can provide clean water to millions of people who lack it.

Many of Westerhoff’s research projects have been funded by agencies such as the National Science Foundation and the Environmental Protection Agency, but he also works with water utilities, non-governmental organizations and industry partners.

“Industry wants to know the answers to things. It’s moved out of the scientific ‘what if’ toward reality,” he said. “They all have agendas and as long as you understand their agendas, they ask interesting questions.”

“As a researcher you want to be focusing on what will be the important question to answer in three to five years, before people even know it’s a question.”

— Regents’ Professor Paul Westerhoff

Westerhoff was commissioned by the environmental activist group Friends of the Earth to see whether there were nanoparticles in powdered infant formula after the manufacturer declined to reveal whether there were.

His lab found needle-shaped nanoparticles in the formula.

“In Europe, there’s a warning on their use in cosmetics but yet they’re in infant formula,” he said.

They discovered the nanoparticles did not dissolve in either water or saliva, but when they put them in stomach fluid, they dissolved instantly.

“They did it to deliver calcium to the gut very efficiently, so they didn’t have to use as much,” he said of the manufacturer. Friends of Earth was concerned that the formula labels didn’t disclose the presences of nanoparticles.

“That’s an example of where one group sees something as a risk to society but a company sees it as a benefit.”

He’s also seen the evolution of how scientific research is portrayed in the media. In 2008, he supervised a doctoral student on a research project that studied the use of nanosilver in socks to eliminate stinky feet. They wanted to know: Did the particles wash out of the socks and into the water supply? The answer was yes.

Journalists jumped all over the story. One headline read, “Toxic socks?”

“We kept telling them the amount of silver is very small and won’t affect anything. None of them got it, and everything they wrote was over the top,” Westerhoff said. “They don’t want to hear that ‘everything is safe, there’s no problem.’ They want to hear ‘there’s nanoparticles in donuts.’ “

In 2015, Westerhoff was named an Outstanding Doctoral Mentor by ASU’s Graduate College. His former students said he is able to deftly balance the guidance that students crave with the independence they need to cultivate.

Troy Benn, who worked with Westerhoff on the nanosilver paper and is now an engineer in Montana, said: “For a young kid it was a little bit shocking because you do all your research in a lab and you don’t talk to anyone outside, and all of a sudden people are asking you what you did.

“Paul’s good at knowing how much guidance each student needs because they’re all unique.”

Kyle Doudrick, who was a graduate student at ASU from 2008 to 2013, said that even with the enormous workload of a full professor, including travel, plus the administrative duties of a vice provost, Westerhoff found time to meet weekly with the students he advised.

“It was a good balance of managing but also letting you find yourself in your independence but not so hands off that you had no idea what’s going on,” said Doudrick, who is now an assistant professor in the Department of Civil and Environmental Engineering and Earth Sciences at the University of Notre Dame.

“The research I did was on nitrate as a contaminant in water,” he said. “He wasn’t the expert but what he was good at was making the student the expert, and that’s the whole purpose of the PhD, is to become an expert at something.”

Even now, Westerhoff teaches ASU 101, the required, one-credit course that all first-time freshmen take.

“I ask them why they want to be engineers, and about half have a life story of something they want to solve. They have a deep passion.

“And if you don’t hear that until you see them in grad school, you’ve lost touch with what motivates people.”

Top photo: Newly named Regents’ Professor Paul Westerhoff spends part of every week supervising students in the hydrology lab where his students work in ISTB4. Photo by Anya Magnuson/ASU Now

Mary Beth Faller

Mary Beth Faller

reporter , ASU Now


Potential funding for Master students in Environmental Engineering

The Directors of Environmental Engineers of the Future (E2F) haveelected to keep the master’s funding application (for 2017-2018 funding) posted into January.
In addition, E2F employers are currently accepting applications for over 20 Civil/Environmental Engineering student jobs (most are summer opportunities requiring no engineering experience that are open to both undergrads and grads).  Students can find jobapplication links via this E2F webpage
We hope this information is helpful for your students, and that you enjoy a wonderful New Year! 

Nano research makes the cover of ES: Nano

Perspective: Overcoming Implementation Barriers for Nanotechnology in Drinking Water Treatment

coverPaul Westerhoff1*, PedroAlvarez2, Qilin Li2, Jorge Gardea-Torresdey3, and Julie Zimmerman4

Nano Impact Statement:

The unique properties that arise at the nano-scale (magnetism, high surface area, selective surface reactivity, surface catalysis, rapid ion delivery, photocatalysis, plasmonic resonance, dielectric properties, electrical conductivity, super hydrophobicity, strength, etc.) can be used to purify drinking water. While discoveries of these processes are reported in the literature, actual products and processes have been slow to mature beyond the bench-scale into larger-scale, constructed systems or consumer point of use devices for purifying drinking water. This perspective article helps identify barriers that can be overcome to enable nanotechnology for water treatment.

Intent on making big impacts

Support from NSF Graduate Research Fellowships is motivating these engineering doctoral students to strive for exceptional achievements

Recipients of National Science Foundation Graduate Research Fellowships are seen by the federal agency as potential leaders in research, teaching and innovation in engineering and science.

Career success for these students is viewed as critical to the United States maintaining its leading role in technological advancement and its strength in national security.

The NSF also counts on the students’ future contributions to boost the vitality of the country’s economy.

The Graduate Research Fellows are awarded a three-year annual stipend of $34,000 and a $12,000 cost-of-education allowance for tuition and fees to pursue graduate degrees.

They also have opportunities for internships, professional development and participation in international research projects, and the freedom to do their own research at any accredited U.S. institution of graduate education of their choice.

Three graduate students in Arizona State University’s Ira A. Fulton Schools of Engineering — each pursuing a doctoral degree — are among the 2016 recipients of the highly sought after NSF Fellowships.


See full story here:   But below is the story that highlights a student in our research group:

national science foundation graduate research fellowship, environmental engineering, resource recovery, educational outreach


Research, teaching and educational outreach are passions

Anjali Mulchandani graduated from the University of California, Los Angeles, in 2014 with an undergraduate degree in civil and environmental engineering. But one of things that most strongly drew her interest there was a presentation by a visiting ASU engineer.

The talk by Fulton Schools Professor Bruce Rittman, director of the Swette Center for Environmental Biotechnology, put ASU on her list of places to explore when she was ready to apply to graduate school.

On her visit she met other ASU engineering professors whose expertise aligned with her interests in water-related engineering.

Now Fulton Schools Vice Dean of Research and Innovation, Professor Paul Westerhoff, a leading water treatment researcher, is her doctoral studies advisor.

Mulchandani, who grew up in Riverside, California, says she misses the ocean beaches that are close to UCLA, “but I have fallen in love with ASU. The environmental engineering community here is great.”

Her research and studies to earn a doctoral degree in the field focus on developing ways to reduce the amount of waste generated and the amount of energy consumed by current and emerging water treatment systems.

She is getting to pursue that goal by working with the ASU team led by Westerhoff that is part of a National Science Foundation Engineering Research Center, the Nanotechnology Enabled Water Treatment Systems center, or NEWT.

She was the president of NEWT’s Student Leadership Council, heading a group of students from each of the four universities that are part of NEWT. They helped to set the direction of the center’s research agenda and to communicate to the public about the center’s work.

Those students are also forming a network to continue collaborations on research as they complete work toward their degrees and embark on their careers.

A main thrust of Mulchandani’s research is atmospheric water capture, involving “a renewable, reusable system that could collect moisture from the air, and then convert it to a liquid phase for use as drinking water,” she explains. “This kind of system could be deployed to provide water in military, disaster relief, or rural off-grid locations.”

She thought it “a humorous but apt take on my work,” when at a research meeting Professor Westerhoff described her dissertation on getting water from the air and gold from waste material as “finding valuable things in unexpected places.”

Along with research, Mulchandani is putting significant time into gaining more experience in teaching, which she also wants to be a major part of her career.

The K-12 education outreach she’s done so far has led her to “fall in love with teaching, especially with teaching young students, because they are so open to learning and get so excited about it,” she says.

Teaching is a valuable skill for scientists and engineers to learn, she adds, “because one way you truly know that you understand your research and can communicate the importance of it is when you have to explain it to a sixth-grader.”

Mulchandani has worked on a National Science Foundation-supported project with Fulton Schools Assistant Dean of Engineering Education, Associate Professor Tirupalavanam Ganesh, that teaches sixth-grade students about water-related science.

She is currently teaching an after-school program in local elementary schools for which she devised the curriculum and the experiments that her young students conduct to learn basic principles of science and engineering.

She has also recruited her fellow graduate students to participate in ASU’s annual Night of the Open Door event that showcases the university’s research endeavors.

“I’m passionate about teaching and outreach, and that’s one of the reasons I like ASU. It does a good job at fulfilling its role as a public university by trying to communicate about the research it’s doing and how it is going to benefit the public.”

Some of the lessons she teaches young students in her education outreach classes are drawn from the research Mulchandani highlighted in the proposal that earned her the NSF Graduate Research Fellowship: her work on methods to recover gold, other valuable metals and bio-oil from sewage sludge.

With her presentation titled “You flushed the toilet, now what?” she teaches students about wastewater treatment plants, metals that are in foods and personal care products that end up in sewage, how sewage and waste are currently disposed of, and new sewage treatment and resource recovery technologies.

Work in those areas not only provided her a topic for her master’s thesis but won her research presentation competitions and awards at a national Sustainable Nanotechnology Conference, at an AZ Water Association Research Workshop, and at a research symposium for ASU graduate students in civil, environmental and sustainable engineering.

She also won the AZ Water Association’s Young Professionals Fresh Ideas competition for a presentation at the AZ Water Association annual conference earlier this year. The association then sent her to the American Water Works Association Annual Conference and Exposition this past summer in Chicago, where she presented her work to a national audience of water science and engineering experts.

Getting support from an NSF Graduate Research Fellowship award to help her pursue career goals in both research and teaching is a big motivator.

The fellowship “is one of the absolute most prestigious things you can aspire to as a graduate student,” Mulchandani says, and it makes her all the more determined “to do work that solves big problems and really helps people.”

Media Contact
Joe Kullman, joe.kullman@asu.edu
Ira A. Fulton Schools of Engineering

10 things to know about ‘Erin Brockovich’ water contaminant

AZ Central and The Arizona Republic report based in part upon our work:

hromium-6, a cancer-causing chemical made famous by the legal efforts of Erin Brockovich, has been found in the drinking water of many major cities, including Phoenix. Wochit

Drinking water with chromium-6 that exceeds California standards for a day or five years won’t change your cancer risk that much, expert says.

Distressed by recent news of the “Erin Brockovich” contaminant in your drinking water?

Don’t panic. Health recommendations are based on decades of exposure, so drinking water exceeding those goals for one day or even for the next five years statistically doesn’t change your cancer risk that much, an Arizona State University scientist said.

A report, released by Environmental Working Group, found that more than 200 million Americans drink water that has more chromium-6 in it than California scientists recommend.

Chromium-6 gained national attention in the 1990s when then-legal clerk Erin Brockovich helped residents in Hinkley, Calif., settle a massive case against Pacific Gas and Electric Co. The electric utility had polluted the groundwater with cancer-causing chemicals, which Brockovich linked to illnesses in the town.

1. The California Office of Health Hazard Assessment set a public health goal of .02 parts per billion.

That means if you drink water containing that amount of chromium-6 over 70 years, you have no more than a one-in-a-million chance of getting cancer. The office determines such goals on health alone — economic or technical feasibility not included.

2. California set its legal limit to 10 parts per billion.

That gives you a 500-in-a-million chance of getting cancer from chromium-6 ingestion. The state arrived at that number based on health, economical and technical feasibility.

3.The U.S. Environmental Protection Agency allows for chromium levels to reach 100 parts per billion.

That lumps together chromium-6 and its benign cousin, chromium-3, but assumes that all of those particles are of the harmful variety. The limit reflects up to a 5,000-in-a-million chance of getting cancer. The federal government set this standard in 2001 based on skin reactions and is considering lowering the limit. But don’t expect a draft assessment until 2017. The EPA reported five years ago that chromium-6 is likely to cause cancer.

4. Chromium-6 leaches into water either naturally or from runoff from industries such as electroplating, leather tanning and textile.

Chromium is an abundant element in Earth’s crust, found in rocks, plants, soil, volcanic dust, humans and animals. Chromium-6 is created when chromium oxidizes. Around here, the contaminant occurs naturally.

5. The contaminant is pervasive.

Environmental Working Group found that Americans drink water exceeding the California goal in all 50 states.

6. Your utility is most likely well within that federal standard, but also within the California standard, if your water system serves at least 10,000 people.

Most utilities in Arizona reported average chromium-6 levels below 10 parts per billion. The testing doesn’t include everyone, though. The law required water utilities nationwide serving at least 10,000 people to test for chromium-6 from 2013 to 2015. A small fraction of small systems were required to test.

7. Home test kits for chromium-6 won’t tell you if you’re within California limits.

Consumer-testing products tend to detect chromium-6 in parts per million. In fact, it’s only been about 10 to 12 years since the technology was developed to measure at the levels we do today. If you’re worried about chromium in your well, you’ll likely have to submit samples to a laboratory to find out if you’re close to California’s health goal, said Paul Westerhoff, senior sustainability scientist of Arizona State University’s Julie Ann Wrigley Global Institute of Sustainability.

8. Techniques to reduce your exposure can be expensive and water intensive.

Reverse osmosis is a method often recommended to reduce your exposure to chromium-6. These systems can cost hundreds of dollars and require vigilance on your part to make sure they’re well maintained and updated with filter replacements on a strict schedule. The technology also wastes about 70 percent of the water it processes, Westerhoff said.

Standard carbon filters will not tackle chromium-6, but the Environmental Working Group has recommended one type of pour-through filter that does. It is unclear, however, whether the product by Zero Technologies filters chromium-6 down to the California standard. The company certifies the product to reduce chromium levels to less than 50 parts per billion.

MORE: Read the report | Learn about your water system on interactive map

9. Make sure the product you buy is certified by the National Sanitation Foundation.

The blue “NSF” label ensures that the product’s claim has been validated.

10. ASU and other university researchers are working with private industry to develop another way to reduce chromium-6 exposure at home.

The team aims to release a technology in about a year that revamps the standard carbon-block filter to combat chromium-6. The work is partially funded by a $3.5 million National Science Foundation grant and membership fees from 15 industrial partners. The goal is to create a filter that is easier to use and less expensive than reverse osmosis, said Westerhoff, who is part of the team.

Chromium-6 in Valley drinking water

Phoenix: 7.9 parts per billion.

Glendale: 6.4 parts per billion.

Avondale: 6.1 parts per billion.

Gilbert: 5.9 parts per billion.

Mesa: 5.6 parts per billion.

Chandler: 5.2 parts per billion.

Peoria: 3.8 parts per billion.

Queen Creek: 3.5 parts per billion.

Scottsdale: 3.5 parts per billion.

Tempe: 2.3 parts per billion.

Source: Environmental Working Group

Note: These numbers reflect an average of all water samples taken from each city’s test sites, which includes lesser-used sources such as wells.