Watching television is exactly like getting involved in any sort of reading books. Whatever affects ethics and religion negatively is Islamically unacceptable, and what is supportive to them is Islamically recommended.
In general, television is like a vessel that could contain something good, as well as it could contain something bad; so it depends on what one watches in it.
An eminent scholar stated: “Not all TV programs are haram. It is haram to watch programs that show nudity or any type of indecency. A Muslim should always select channels and programs that are beneficial, educational, and informative. If, by accident, one happens to see any indecent thing, one should turn the TV off forthwith. In fact, the problem is not in the TV as a machine but in what a person sees in it. If one watches documentary movies, news, educational and Islamic programs, then there is nothing wrong in watching TV so long as the TV does not distract the person away from his/her Islamic duties such as prayer”.