Answer
In the Name of Allah, Most Gracious, Most Merciful.
All praise and thanks are due to Allah, and peace and blessings be upon His Messenger.
In this fatwa:
Married couples can bath together. Prophet Muhammad (peace be upon him) used to take a bath with his wife. Also, married couples can have sex in a bathroom.
In responding to your question about having sex in a bathroom, Sheikh M. S. Al-Munajjid, a prominent Saudi Muslim lecturer and author, states:
It is permissible for a man to have intercourse with his wife without a cover. It is also permissible for couples to have sex in a bathroom. But that means that he will be going against the Sunnah by not mentioning Allah beforehand.
Perhaps you know that the Sunnah, when a man wants to have intercourse with his wife, is to say,
‘Bismillah, Allahumma jannibna ash-Shaytana wa jannib ash-Shaytana ma razaqtana (In the Name of Allah, O Allah, keep Satan away from us and from that with which You may bless us).” (Al-Bukhari and Muslim)
Almighty Allah knows best.
Editor’s note: This fatwa is from Ask the Scholar’s archive and was originally published at an earlier date.
Source: www.islamqa.info/en