bowser vs cistern

bowser

noun
  • A mobile water tank deployed to distribute fresh water in emergency situations where the normal system of piped distribution has broken down or is insufficient. 

  • A buffoon or imbecile. 

  • A road vehicle (often a trailer) for the transport of liquid fuel, particularly aviation fuel at an airfield. 

  • A fuel metering/delivery pump at a filling station. 

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 bowser and cistern occurred in a corpus of books? (source: Google Ngram Viewer )