According to NPR, because the researchers only analyzed the samples for genetic signatures of different pathogens, they couldn't determine whether the bugs were alive, and potentially reproducing in the water, but there were no pool-related diseases reported in Atlanta during the summer the samples were gathered.

CNN: Yuck! What's in your pool water

Currently the samples are used to hunt for specific genetic variants between twins that might account for health-related behaviors and conditions, such as how much people eat or how much coffee they drink, says Patrik Magnusson, the registry's head of research.

WSJ: Twins Health Registry Is Treasure Trove for Medical Research