Newswise — SAN DIEGO, March 23, 2022 — The next generation of scientists and inventors is already finding approaches to address society’s problems. Today, a group of high school students and their instructor report a solution to the problem of lead contamination in drinking water — an inexpensive faucet attachment that removes this toxic metal. Unlike conventional filters currently on the market, theirs includes a cartridge made with biodegradable plastic and indicates when it’s “used up” by turning the tap water yellow.

The researchers will present their results today at the spring meeting of the American Chemical Society (ACS). ACS Spring 2022 is a hybrid meeting being held virtually and in-person March 20-24, with on-demand access available March 21-April 8. The meeting features more than 12,000 presentations on a wide range of science topics.

“A few years ago, I saw a video of a woman in Michigan turn on her tap water, and it came out brown,” says Rebecca Bushway, who is the project’s principal investigator. She’s also presenting the work at the meeting. “That made me think — because there’s really no safe level of lead in drinking water, wouldn’t it be nice to have a water filter that could tell you that your water is contaminated, well before it turns brown because of lead?”

Although some pipes have been remediated in the U.S., millions of homes, especially those in low-income communities, still receive drinking water through lead-containing pipes. If the water’s chemistry isn’t ideal, or it flows quickly because of high demand, then pipes can corrode. When the corroding material contains lead, the toxic metal dissolves or flakes off into the water, contaminating it with a dark discoloration and sometimes visible particles.

Until old pipes can be replaced with lead-free versions, filters can help remove or reduce this pollutant from tap water. Although various lead filtration systems exist, their high cost and large size can be barriers. In addition, few of them provide any indication that they should be changed, and none indicate that the water could pose an immediate health risk.

Bushway, a science teacher at Barrie Middle and Upper School, wondered aloud to her upper-level high school chemistry class if there was a little filter — similar to the ones that are made for camping to purify water — that they could make from inexpensive components to easily remove lead. The students were excited about the idea, and they started thinking about the project in 2020 when COVID-19 restrictions kept them out of the classroom. While at home, the team met virtually and discussed designs for an attachment to screw a filter onto a sink’s faucet. Then in the spring semester of 2021, when they returned to the classroom, they 3D printed the attachment and a 3-inch-tall filter housing, using a biodegradable plastic. Their final step was to fill the cartridges with a mixture of calcium phosphate and potassium iodide powder.

“Calcium phosphate first binds with dissolved lead in water to form lead phosphate and free calcium. The calcium, which is harmless, ends up in the water, and the lead phosphate stays in the filter,” explains Bushway. Lead phosphate, which is an inert solid, is trapped inside the filter by a nylon screen on the bottom of the unit. Once the reaction capacity of the calcium phosphate is reached, dissolved lead reacts with potassium iodide, which turns the water yellow, an indicator that lead is present. 

And while the chemistry itself is pretty straightforward, crafting the water filtration system to do what the researchers intended has been more complicated. For instance, calcium phosphate tends to clump up, causing the reaction rate between it and lead to go down as the surface area decreases. So, the team’s lead student engineer incorporated hexagonal bevels inside the filter. “That’s an innovation, which came from one of the high school students, that will make the water spiral as it goes through and keep the powder from clumping,” says Bushway.

Next, the students will add a tiny spectrophotometer with a single-wavelength LED to the bottom of the filter cartridge, where the water gets dispensed. Their plan is to have an indicator light that turns on as soon as the detector identifies the yellow color of the lead iodide. Bushway says this will indicate that lead is in the water, even before the color is detectable by a human eye.

The team’s goal is to make and sell their filters for less than $1 each, which Bushway thinks they’re on their way to doing. Because the housings use biodegradable plastic, the cost could trend a little higher, but the material would help reduce the overall environmental impact of the filter.

The process of developing the filter has been very fulfilling, according to Bushway. “Ultimately, this experience has shown students that they can make a difference to somebody, and there are problems that they can fix with science,” she says.

The researchers acknowledge support from Barrie Middle and Upper School.

A recorded media briefing on this topic will be posted Wednesday, March 23, by 10 a.m. Eastern time at

ACS Spring 2022 will be a vaccination-required and mask-recommended event for all attendees, exhibitors, vendors, and ACS staff who plan to participate in-person in San Diego, CA. For detailed information about the requirement and all ACS safety measures, please visit the ACS website.

The American Chemical Society (ACS) is a nonprofit organization chartered by the U.S. Congress. ACS’ mission is to advance the broader chemistry enterprise and its practitioners for the benefit of Earth and all its people. The Society is a global leader in promoting excellence in science education and providing access to chemistry-related information and research through its multiple research solutions, peer-reviewed journals, scientific conferences, eBooks and weekly news periodical Chemical & Engineering News. ACS journals are among the most cited, most trusted and most read within the scientific literature; however, ACS itself does not conduct chemical research. As a leader in scientific information solutions, its CAS division partners with global innovators to accelerate breakthroughs by curating, connecting and analyzing the world’s scientific knowledge. ACS’ main offices are in Washington, D.C., and Columbus, Ohio.

To automatically receive press releases from the American Chemical Society, contact [email protected].

Note to journalists: Please report that this research was presented at a meeting of the American Chemical Society.

Follow us: Twitter | Facebook | LinkedIn | Instagram

Water, water everywhere, but not a drop to drink

Lead contaminated drinking water is not isolated to Flint MN, there are cities across the country and around the world struggling to keep lead out of their water supply. Expensive filters and bottled water are only a stop-gap measure. The purpose of this work was two-fold: to expose high school students to academic research and to produce an inexpensive filter for lead. The most important aspect of the filter was to remove lead from contaminated water. However, an issue occurs when filters are used longer than they are effective. The solution to this problem was to create a filter pack with an indicator that changed the color of the water when lead was present. A filter was manufactured in the maker-space of the Barrie Middle and Upper School that would affix to a standard faucet or water bottle. The filter contained a packet of calcium phosphate and potassium iodide. As contaminated water was poured through the filter, lead reacted with the phosphate to produce bio-unavailable lead (II) phosphate. As the calcium phosphate was consumed, allowing lead to pass through the filter, potassium iodide reacted with the lead, changing the color of the water to yellow. This yellow color indicated that the water was contaminated, and should not be drunk. A solution of 20 ppm lead (II) nitrate solution was passed through the filter. Samples indicate that lead was no longer present. Once the stoichiometric maximum phosphate had been consumed, the solution turned yellow, indicating that lead (II) iodide had been produced. This filter is inexpensive, removes a harmful contaminate from drinking water, and alerts people when it is no longer working. It should also be noted that this research was conducted by high school students while under quarantine, and in their own chemistry classroom.