Chlorine can kill sperm, however, if a couple is having intercourse in a pool, there is still a definite possibility that pregnancy can occur. That said, please do NOT consider a swimming pool or any body of water with chlorine as a method of having safer sex. If you are considering having sex in a swimming pool, there can be some issues with using condoms (as described in detail in the question listed below), so FX strongly recommends that you use a back-up method of birth-control, such as the pill or patch if you are trying to protect yourself against unwanted pregnancies. Keep in mind, however, that this is definitely not an ideal situation as the pill and patch do not offer any protect against the transmission of STDs.
To learn more about using condoms in water and the effect of chlorine on condoms, please read the answer to “Can You Use Condoms in Water?” under the Birth Control Methods section of the website.
If you have any further questions about safe condom usage, read the instructions that come with the condom package and speak with your healthcare provider. If you don't have a doctor and live in northern