Think you can't get pregnant if you have sex in the water? Wrong. You get zero protection from pregnancy by having sex in a pool, bath, or shower as long as vaginal sex occurs, where penetration is involved.

On the flipside, some people are scared of getting pregnant from swimming in a pool that a guy has ejaculated in. That's not going to happen, either – sperm can't do the backstroke through the pool water, somehow find their way into a vagina on their own, and cause a pregnancy.

Reference: https://www.plannedparenthood.org/teens/sex/the-ten-biggest-myths-about-sex/