washbasin vs washtub

washbasin

noun
  • A laundry sink. 

  • A basin used for washing, (now) particularly a permanently installed sink, fitted with a water supply and a drain, for washing the hands and face. 

washtub

noun
  • A tub used for washing clothes. 

How often have the words washbasin and washtub occurred in a corpus of books? (source: Google Ngram Viewer )