For what it's worth there are other considerations like wastewater processing capacity, especially when it rains

See e.g. https://www.nyc.gov/assets/dep/downloads/pdf/whats-new/progr...

https://www.apartmenttherapy.com/shared-sewer-systems-househ...

https://d3.harvard.edu/platform-rctom/submission/the-dirty-t...