catchment vs cistern

catchment

noun
  • Any structure or land feature which catches and holds water; the collection of such water. 

  • A catchment area, or the people it serves. 

verb
  • To divide into catchment areas. 

cistern

noun
  • A reservoir or tank for holding water, especially for catching and holding rainwater for later use. 

  • The vessel surrounding the condenser in a steam engine. 

  • In a flush toilet, the container in which the water used for flushing is held; a toilet tank. 

  • A cisterna. 

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