There is nothing wrong in husband and wife taking bath together. This is a kind of enjoyment and type of fondling that depends on the consent of the spouses. It is not a function of religion to determine the way a couple should enjoy each other. The only restrictions in the domain of intimate relations are anal sex and sex during menstruation and post-natal bleeding. Apart from these forms, nothing is haram.
In his book Aadab Az-Zifaf Fi As-Sunnah Al-Mutahharah, the late Sheikh Muhammad Nasiruddin Al-Albani, states the following: It is permissible for the husband and wife to take a bath together in the same place even though he sees her private parts, and she sees his. This is established by a number of authentic hadiths, among which are the following:
1. On the authority of ‘Aa’ishah (may Allah be pleased with her) who said: “I used to bathe with the Prophet (peace and blessings be upon him) from a single container of water which was placed between us such that our hands collided inside it. He used to race me such that I would say: `Leave some for me, leave some for me!’ She added: `We were in a state of janabah (i.e. post-sex state).” (Reported by Al-Bukhari and Muslim.)
2. On the authority of Mu’awiyah Ibn Haida, who narrated: “I said: ‘O Messenger of Allah, which of our ‘awrah is allowed (to uncover), and which one must we beware of (uncovering it)?’ The Prophet answered, “Guard your `awrah except from your wife or those whom your right hand possesses.”
Thus, it is permissible for both spouses to look at and touch the body of his or her companion even the private parts. He said: ‘O Messenger of Allah, what about if the relatives live together with each other?’ The Prophet answered: “If you can make sure that no one ever sees your `awrah, then you can do so (uncover it).” He said: ‘O Messenger of Allah, what about when one is alone?’ The Prophet replied: “Allah is more deserving of your bashfulness than are the people”.” (Authentic Hadith reported by Ahmad, Abu Dawud, At-Tirmidhi and others.)