I've been thinking a lot about the civil engineering projects that underlie pre-industrial cities, and sewers are a really important part of that. They're also a lot older as a technology than I realized... but also, when I was doing the research for this, my son saw one of the practical engineering videos and I spent about half an hour watching big animals poop as a consequence.
- Ancient Mesopotamians used bitumen (natural tar) to plug leaks in irrigation and sewage systems. These irrigation systems functioned until the 1200s, when they were destroyed by Mongolian invaders.
- Poor Babylonians used the streets as trash cans and sewers, which were periodically re-paved with clay. This raised the level of the streets over time, so stairs had to be built so the houses could still be accessed.
- The Aztecs dealt with sewage through a complex filtration system similar to modern septic tanks.
- Anatomically shaped toilets began appearing in Hellenistic homes and public buildings during the Bronze Age.
- Egyptian pyramids from 4,500 years ago had sophisticated copper drainage systems.
We aren't entirely sure how the Maya used pressurized water, but we know they were able to engineer water pressure before the arrival of the conquistadors. Aqueducts were pretty common in their city of Palenque because there was limited land available, so routing the water underground helped preserve area for living spaces. Pressurized water might have been used to make fountains, either for aesthetics or for drinking water. It might also have been used as a sort of pump for wastewater disposal.
Gravity is a very useful helper when it comes to getting sewage away from city centers, but sewer pumps also play a really important role. Modern pumps sometimes have moving screens to keep them from getting clogged, as well as sharp cutters that function like garbage disposals to keep large solids out of the expensive machinery. Most sewers are designed to handle 250 gallons of sewage per capita per day. Flow rate is required to be 1 meter per second -- here's a great video demonstrating why.
Wealthy Assyrians had 15sqft brick-lined bathrooms with drainage systems; the palace of Sargon the Great had seated toilets with drains that discharged into a main sewer line. Came across a really nice article about clay sewer pipes. There are a lot of really useful pictures of Babylonian sewer joins and photos of towns with hot and cold running water in 1000 BCE in the Levant.
Ancient Beijing used super-absorbent pavers, along with underground culverts, to deal with stormwater management. The drainage technology was set up at least 2,200 years ago; the sewage system in Xi'an used pre-cast ceramic pipes, some of which seem shaped like hexagons, rather than being round.
📗 If you found this interesting, you may also enjoy the city walls edition.
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