pipework vs water pipe

pipework

noun
  • Any system of pipes or tubes; piping 

  • The pipes and stops of an organ 

water pipe

noun
  • A pipe that is a conduit for water; an essential element of plumbing. 

  • A device for smoking, such as a hookah or bong, in which the smoke is drawn through a container of water before inhaling. 

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