According to the Centers for Disease Control and Prevention (CDC), studies “show that head lice can survive under water for several hours but are unlikely to be spread by the water in a swimming pool.”
Head lice hold tightly onto the child’s (or adult’s) hair and essentially hold their breath when under water. Contrary to some peoples’ opinions, chlorine does not kill head lice.
It is also important to know that head lice can be spread when children share towels, washcloths and any other items that have been in contract with the hair of someone who had head lice. In additional to towels this applies to other bathing accessories like hairbrushes, combs, curlers, etc.
Also, the CDC reports, “Swimming or washing the hair within 1–2 days after treatment with some head lice medicines might make some treatments less effective.”