The Wikipedia page is pretty good: https://en.wikipedia.org/wiki/Demographic_transition
(Not a sociologist, but used to be married to one.)
Plus you can solve climate change AND road traffic!
Please explain to me how you plan to enforce your ban on people having more than one kid.
Do you suggest imposing those restrictions elsewhere? Via what means, and how do you intend to enforce this within those countries?
Don’t get me wrong, I’m not saying the problem is insurmountable, but it does actually need to be dealt with somehow rather than just hoping tech will save us when we need it — that approach works fine right up until it fails catastrophically.
https://en.wikipedia.org/wiki/Projections_of_population_grow...
We do waste water, but this is besides the point. The point is that you could have the best resource extraction technologies, but if there are no resources left to extract due to depletion, then you are pretty much borked.