For many across the globe, access to clean water is not guaranteed. In recent years, atmospheric water harvesting has started to look like a promising solution for water production. Some technologies are even being developed to pull water directly from the air inside a home or office building.
On Thursday, in a presentation for the Division of Environmental Chemistry at ACS Fall 2026, Arizona State University (ASU) undergraduate researcher Emma Mast highlighted how indoor pollutants may affect the quality of water pulled from the air. Mast and her coauthor, PhD candidate Joshua Quinn, are working on the interdisciplinary project with engineer Paul Westerhoff and atmospheric chemist Pierre Herckes.
“One of the testing facilities we use in this project is my house. So I collect the water and then do all of the water quality analysis,” Mast said.
For months, Mast has collected water from the air in her bedroom, as well as from a living room in another home and an apartment kitchen. She collected water from each location using commercial sorbent–based water generators designed to produce drinking water; she also used commercial dehumidifiers. In addition, Mast collected air samples directly from those spaces using sorbent tubes.
With samples in hand, Mast used instrumentation in the Westerhoff lab at ASU to measure a variety of water quality metrics, including pH and total organic carbon (TOC). Mast found that both metrics were location dependent. Further, all the water produced indoors had significantly higher TOC content than water collected from an outdoor patio.
Mast also compared the concentrations of various aldehyde species present in the air and in the water collected from the same rooms. “We see a lot of acetaldehyde and acetone in the air, especially in the bedroom,” she said. But the same ratio doesn’t appear to be in the water, where the concentration of formaldehyde dominates.
“We have tried to use Henry’s law as a way to understand what we might expect to find in the water from the air concentrations,” Mast said. According to those calculations, she added, “there is 10 times more formaldehyde in the water than what we expect [at equilibrium].”
Importantly, the sorbent-based water generator collected less aldehydes than the dehumidifier. Reflecting on the project, Mast said she and her team hope that their findings spark conversation about how best to treat water pulled from the air in indoor spaces.
After seeing the presentation, session presider Rachel O’Brien, an atmospheric chemist at the University of Michigan, said the work Mast shared will interest indoor-air researchers. “I appreciate the fact that the work they are doing can be used to better understand indoor air components, and it will help improve development of water-capture technology,” O’Brien wrote in an email. Other scientists are using mist chambers to explore how water-soluble gases partition into water. Collecting water with dehumidifiers, as Mast did, “would be even easier to use because people already use them in their homes,” O’Brien added.
