river basin vs washbasin

river basin

noun
  • An extent of land where water from rain or snow melt drains downhill into a river or series of rivers. 

washbasin

noun
  • 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. 

  • A laundry sink. 

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