The Etruscans laid the first underground sewers in the city of Rome around 500 BC. These cavernous tunnels under the city streets were built of finely carved stone and the Romans were happy to use them when they took control of the city. Such structures then became the norm in many cities of the Roman world.
Focusing on life in ancient Rome, Pompeii, Herculaneum and Ostia, I am deeply impressed by the brilliant engineers who designed these underground wonders and the magnificent architecture that masks their functional purpose. Sewer tunnels did not run under every street, nor did they serve every area. But in some cities, including Rome itself, the length and breadth of the main sewer, the Cloaca Maxima, rivals the length of the main sewer lines in many cities today. We should not assume, however, that Roman toilets, sewers and water systems were built with our own modern sanitary goals in mind and with our microbiological knowledge.
I would like to make a comment: it seems to me ⁹ that the judgment on Roman society and in particular on hygiene should be contextualized. I read numerous criticisms, especially by English-speaking writers, on the presence of lead in water, on the development of microorganisms, on the dirt of the streets and even on gas explosions in public latrines. Some also said that the pipes were leaking resulting in air pollution.
I would like to remind those who argue that the baths were a breeding ground for germs and parasites, as they were stagnant, that the water was flowing and constantly changing. Same thing for lead pipes.
The Romans still came out of the baths clean and perfumed.
The latrines that did not communicate with the sewer system were regularly cleaned by dung men.
Crews cleared the streets of litter.
In highly civilized England in the 1800s the streets were covered with straw mixed with dung and cholera was rampant.
Sorry if I rambled on a bit.