Yeah, that has more to do with American social issues and lack of government support for the general population. Water engineering is expensive no matter where or when you are, and America is huuuge.

Plumbing was common in the ancient world in the Near East, Middle East, Mediterranean (Greece and Rome), and really wherever there were people. Keep in mind if you ask two different archaeologists, you’ll get two slightly different answers, but it’s pretty common knowledge that running water is not a modern invention.

Some sources (only a quick search, I don’t have access to all the academic journals where you’d find the good stuff):

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7004096/

https://ancientengrtech.wisc.edu/greece-overview/water-systems/

https://education.nationalgeographic.org/resource/roman-aqueducts/

https://en.m.wikipedia.org/wiki/Ancient_Greek_technology

https://whc.unesco.org/en/list/1506/ <–this one is really cool, the Qanats are still fully functional today

Edit: fixed links

My favourite example:

https://www.ucl.ac.uk/news/2023/aug/chinas-oldest-water-pipes-were-communal-effort

A system of ancient ceramic water pipes, the oldest ever unearthed in China, shows that neolithic people were capable of complex engineering feats without the need for a centralised state authority, finds a new study by UCL researchers.

this would be residential, if we’re just talking “indoor plumbing” than i would assume it doesn’t have to include residential spaces, and probably applies to things like public baths, and bathrooms/latrines or whatever for example.