hydro vs mains

hydro

noun
  • electrical power supply; specifically, electrical power provided by a utility (as a publicly-owned one); payment or bills for this. 

  • hydroelectric power 

adj
  • hydroelectric 

  • hydroponic 

mains

noun
  • The domestic electrical power supply. 

  • The pipes of a centralized water supply that transport the water to individual buildings. 

  • The farm attached to a mansion house. 

  • The main course of a meal. 

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