The earliest known flush toilet dates from 1800 b.c. Featuring a wooden seat, it was installed in the royal palace at Knossos in ancient Crete and used a drainage system with venting air shafts. Water-flushed latrines were in use in the Indus Valley circa 2500-l500 b.c., and by the fourth century a.d. the Romans used them as well. The flush toilet then disappeared for many centuries, and chamber pots, emptied into public streets, became the norm in Europe during the Middle Ages.

The concept of the flush toilet was finally revived around 1590 by Queen Elizabeth's godson Sir John Harington (l561-l6l2). He designed and had installed in his home a water closet that featured an overhead water tank with a valve that released the water on demand. Although the queen had one of her godson's inventions installed in her palace, the water closet did not...