In London, the contents of the city's outhouses were collected every night by commissioned wagons and delivered to the nitrite beds where it was sown into the special soil beds to produce earth rich in mineral nitrates.
The Classic Maya at Palenque had underground aqueducts and flush toilets; the Classic Maya even used household water filters using locally abundant limestone carved into a porous cylinder, made so as to work in a manner strikingly similar to Modern ceramic water filters [REF].