In brief:Three brands of plastic tennis ball containers were tested to determine whether they were safe receptacles for drinking water. The containers were cultured for bacteria and viruses immediately after they were opened. Then they were filled with organic-free water; water samples were analyzed for organic compounds immediately after they were filled, every 30 minutes for two hours, and at 20 hours. Culture results showed that the containers were sterile, but chemical analyses of the water samples yielded low levels of toluene, trichloroethane, and thiocyanic acid. Although the amounts of these compounds were not toxic, the authors recommend that tennis players rinse the containers thoroughly at least once before using them to hold drinking water.