To make drinking water safer, researcher investigates microbial communities living in pipes

An engineer at West Virginia University is working to solve the unknowns about microorganisms growing inside pipes that bring drinking water to homes and businesses.

Supported by a U.S. National Science Foundation grant, researcher Emily Garner has launched a study to learn more about biofilms. Known as "cities of microbes," biofilms are conglomerations of fungi, algae, bacteria and other single-celled organisms that cling to each other and to surfaces like the insides of water pipes, where they become coated in protective slime.

"Many things influence how biofilms grow in drinking water distribution systems: water chemistry, the presence of disinfectants like chlorine, and the forces exerted as water flows through pipes," said Garner.

"The goal is improving the quality and safety of drinking water at the points of consumption."

"But past research about biofilms doesn’t account for the complexities of varied flow conditions in different parts of a water distribution system. These systems can consist of hundreds of miles of buried pipes, so ensuring the chlorine disinfectant hasn’t decayed by the time it reaches all parts of the system can be a challenge."

Garner will develop strategies for maintaining water quality throughout these complex infrastructures and offer recommendations to managers of drinking water distribution systems.

Garner said that “it’s normal and expected for biofilms to form on the inside of all drinking water pipes. Biofilms rich in organisms that are harmless to humans may even be effective at reducing the growth of harmful pathogens through competition.”

But biofilms can be also detrimental to drinking water quality. The protective environment they create can harbor dangerous microorganisms like salmonella or E. coli, and they can release particles or compounds that affect the taste, odor and color of tap water. They can also facilitate formation of harmful compounds called “disinfection byproducts.”

Garner said that water utilities control the growth of microorganisms by adding small amounts of a disinfectant like chlorine into the water.

"At low enough levels, these disinfectants are not harmful to humans but prevent growth of microorganisms like those in biofilms," she said. "This is important for making sure the water that arrives at your home is high-quality and safe, even though it has made a long journey of many miles from the treatment plant."

To evaluate ways to minimize potential safety hazards, Garner will combine lab experiments with field sampling from water systems throughout West Virginia, where water quality can vary dramatically between communities.

"This project will benefit society through the generation of fundamental knowledge to guide the management of drinking water distribution systems," says Mamadou Diallo, a program director in NSF’s Directorate for Engineering. "The goal is improving the quality and safety of drinking water at the points of consumption."