facilities vs necessarium

facilities

noun
  • Facilities for urination and defecation: a toilet; a lavatory. 

  • Synonym of facility in certain contexts. 

necessarium

noun
  • A lavatory. 

  • Synonym of reredorter: a monastery's latrine, outhouse, or lavatory, typically located behind the dormitory. 

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