Microbial communities in slow sand filters for drinking water treatment adapt to organic matter altered by ozonation.

Changing natural organic matter quality from anthropogenic activity and stricter requirements for micropollutant removal challenges existing systems for drinking water production. Ozonation of water followed by biofiltration, such as passage through a slow sand filter (SSF), is a partial solution. Biofiltration relies on biofilms (microbial communities within extracellular matrices).