Whether one is visiting friends or relatives, one must avoid unnecessary requests that may inconvenience the host. For example, using the phone, going to the toilet or performing ablution.
Good manners dictate that you should be considerate, for not every house may have facilities prepared for the use of guests. The condition or location may cause embarrassment or inconvinience to the host or the family of the host.
One should prepare for things before leaving home, in order to minimise the potential inconvience or burden on the host. A host can only be pleased at a burden-free, non-embarrassing visit; and will enjoy your visit more as a result. One should always consider the convenience and appropriateness of ones actions when visiting.