After high-profile water problems like the crisis in Flint, Michigan, many Americans worry about the safety of their tap water.
Because of this fear, some people choose to buy drinking water from freestanding machines called water kiosks. Stores and public places often house these kiosks. People usually pay about $0.25 to $0.35 per gallon of water. In comparison, tap water in most U.S. cities costs less than 2 cents per gallon. Many consumers think kiosk water is safer than tap water.
But a new study shows that the water from these machines may have different types of pollution than local tap water. Researchers from the University of Iowa studied 20 water kiosks across six states: Iowa, Illinois, Kansas, Missouri, Arkansas, and Oklahoma.
They collected samples of water from kiosks. While some samples were collected from tap water from the closest community sources to the kiosk. The researchers wanted to check the water for chemicals and microbes and to see how kiosk water compared to tap water. Water kiosks are private machines that usually treat tap water before selling it.
Common treatment methods include filtration, ultraviolet (UV) light, and reverse osmosis (RO). RO pushes water through a special membrane using pressure. This process removes many contaminants, such as chemicals, tiny particles, and some metals. Water kiosks often promote RO as a method to make water safer. It can remove harmful substances, including lead and PFAS, which are chemicals that can stay in tap water.
The study found some good news. Water samples from kiosks and taps had no microbial contamination. This means there were no harmful bacteria or germs. RO treatment in kiosks removed most PFAS, a chemical that can harm health if it builds up in the body. However, there was also a worrying problem. Some kiosk water had lead above the safe levels recommended by the U.S.
Environmental Protection Agency. The researchers discovered that the lead came from the metal parts inside the kiosks. The kiosks use brass plumbing pieces, which are labeled as “lead-free.” But even small amounts of lead can leak from these pipes when the water has low pH or low alkalinity, which happens after RO treatment. This phenomenon means that even water treated to remove harmful substances can still pick up lead from the plumbing before it comes out of the machine.
The scientists suggest a potential solution to this problem. Replacing the metal parts inside the kiosks with materials that do not contain lead could remove this risk. “This work adds to growing evidence that ‘lead-free’ plumbing can still be a source of lead in drinking water under certain conditions, like after RO treatment,” said David Cwiertny, one of the study’s authors. Samantha Zuhlke, another lead author, said, “Currently, water kiosks are not regulated the same way as tap water. Their water is not tested for lead or other metals.
Updating the rules for water kiosks can make the water safer and help people make better decisions about what they drink.” Kiosks are often marketed as a safer option, but this study shows that they are not automatically risk-free. People who choose to buy kiosk water may get some benefits, such as fewer PFAS chemicals, but they could also be exposed to lead if the machine’s plumbing is not properly designed. This finding highlights the need for better rules and monitoring of these machines.
The study was supported by the University of Iowa’s Center for Social Science Innovation and the Office of Undergraduate Research. It was conducted through the University of Iowa Center for Health Effects of Environmental Contamination, which is supported by the Iowa Department of Natural Resources.
