Conversation so far:
Tell me about the history of toilets.
It was actually 300 years earlier, during the 16th century, that Europe discovered modern sanitation. The credit for inventing the flush toilet goes to Sir John Harrington, godson of Elizabeth I, who invented a water closet with a raised cistern and a small downpipe through which water ran to flush the waste in 1592.
Where does the term toilet come from?
mid 16th century: from French toilette ‘cloth, wrapper’, diminutive of toile (see toile). The word originally denoted a cloth used as a wrapper for clothes; then (in the 17th century) a cloth cover for a dressing table, the articles used in dressing, and the process of dressing, later also of washing oneself (toilet (sense 2 of the noun)). In the 19th century the word came to denote a dressing room, and, in the US, one with washing facilities; hence, a lavatory (early 20th century).
Where and when was the first toilet invented?
Although Harington installed a working model for Queen Elizabeth at Richmond Palace, it took several centuries—and the Industrial Revolution's improvements in manufacturing and waste disposal — for the flush toilet to catch on. In 1775 English inventor Alexander Cumming was granted the first patent for a flush toilet.
Why do the Brits call a toilet a loo?
“Loo” comes from either French “l'eau” - water - or Waterloo, a trade name for early cisterns. In the days when people emptied their bed pans into the street, from an upper bedroom window, it was polite to warn passers-by to call Gardez l'eau!
What came before toilets?
In 1596 Sir John Harrington invented a flushing lavatory with a cistern. However the idea failed to catch on. People continued to use chamber pots or cess pits, which were cleaned by men called gong farmers. (In the 16th century a toilet was called a jakes).

Question: When did indoor versions become common
Self-contained rewrite: When did indoor versions of toilets become common?