There was a time when you were practically guaranteed to find a set of these in the loft when moving into a new home.
It seems to me that they are becoming rarer so hang on to yours if you have one. Every bedroom used to be furnished with a wash stand with a porcelain bowl and water jug, plus any number of optional extras, like a soap dish.
Warm water was supplied in the jug from the kitchen and poured as required by the user. Better off people had the warm water brought up by a servant and the dirty water whisked away when finished with.
No servants? – you probably just washed in the kitchen sink, but guests might get this luxury as described in this link: http://www.1900s.org.uk/1900s-guest-facilities.htm