Nanoplastics were studied to see how well they are removed during drinking water treatment. The researchers used special labeled particles to track the nanoplastics through different treatment processes like ozonation and filtration. They found that aged sand with biofilm was the most effective at removing nanoplastics. A computer model showed that a combination of rapid sand filtration, activated carbon filtration, and slow sand filtration could remove over 99.9% of nanoplastics. Slow sand filtration was the most important step in removing nanoplastics. This study helps estimate how well typical drinking water treatment plants can remove nanoplastics from water.