Having sex in a pool or Jacuzzi poses a higher risk of infection. According to research at the University of California, Santa Barbara, water teeming with microbes can get forced into the vagina. “Sometimes residential (and commercial) hot tubs, pools and Jacuzzis are not chlorinated adequately, increasing the amount of bacteria they contain and the likelihood of an infection. Even if the water has a chlorine level in accordance to government standards, there is still a risk of infection.” Also, “chlorine may disrupt healthy bacteria and change the natural pH in the vagina leading to a yeast infection.”
Having sex in the ocean or a lake can also pose problems. Although these places do not pose chemical/chlorine issues, according to Health & Sexuality columnist, Lisa Hermann, you should “be aware that natural bodies of water have the potential to harbor some unusual bacteria and/or amoebas” which could put a woman at risk for a urinary tract infection.
Women are more susceptible to infections during water sex due to their anatomical differences. This risk includes sexually transmitted infections, urinary tract infections, yeast infections, and the added issue of sexual friction (due to less lubrication) that can result in irritation and micro-tears to the vaginal walls. These tears open up a direct route for infections and could increase the chances of catching a sexually transmitted disease.