One of the top searches on Google regarding where you can get sexually transmitted diseases from show that people are curious about whether or not they can contract an STD from swimming pools.
This query ranks fourth after asking in a Google search if you can get STDs via kissing, a toilet seat, or oral [sex].
Don’t make a splash because you CANNOT get an STD from swimming in a pool or relaxing in a hot tub. Appropriate chlorine and chemical levels are maintained to kill bacteria and viruses, including those that cause sexually transmitted diseases.
STDs are typically transmitted during sexual contact and, as of yet, there are no documented cases of anyone contracting an STD from swimming in a pool.
If you are going for a swim, just avoid sharing towels. Public lice (crabs) and the virus molluscum contagiosum can be spread by sharing infected linens including bedding, clothing and towels.