downspout vs waterway

downspout

noun
  • A vertical pipe or conduit that carries rainwater from the scupper, guttering of a building to a lower roof level, drain, ground or storm water runoff system. 

waterway

noun
  • A conduit or watercourse, such as on the deck of a ship, to drain water. 

  • A body of water, such as a river, channel or canal, that is navigable. 

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