These are a little rough to look at. While for a long time this has been typical of what humanity has been using but it just doesn't scale. This almost works when populations are small and the environment can adsorb it but at the scale of millions of people the environment is overwhelmed. This is also a prime source for disease.
Come on the Romans figured this out over 2000 years ago and we still haven't got the entire planet up to that tech level yet. How stupid!