Short answers, pulled from the story.
419 million people have no access to a toilet at all and must openly defecate in the open air. This lack of infrastructure leads to diseases transmitted via the fecal-oral route such as cholera and dysentery.
The city of Uruk in Mesopotamia exhibits the earliest known internal pit toilet from the fourth millennium BC. Neolithic village Skara Brae in Orkney contained small rooms over communal drains around 3100 BC.
Scottish mechanic Alexander Cummings invented the S-trap in 1775 which uses standing water to seal bowl outlets. Water closets started appearing inside homes around 1850 after being located outside previously.
Toilet originated as a French loanword first attested in 1540 referring to little cloth draped over shoulders during hairdressing. The term came to describe grooming complexes centered at dressing tables covered by cloths around late 17th century.
Vacuum toilets remove waste by suction using less than a quarter liter per flush operation. Astronauts on the International Space Station use space toilets recovering potable water through urine diversion.