Mostly personal experience including some stories from permaculture types who've been approaching these problems for a while. I'm designing a habitat that will

Mostly personal experience including some stories from permaculture types who've been approaching these problems for a while. I'm designing a habitat that will have an additional complication of both low-pressure gravity fed and electric-pump (city pressure) circuits. Regulations lag behind optimum configuration, though parts of EU, especially in the north, legislated triple-glazing (f.e.) quite a few years ago (can't find a cost analysis of break-even points, unfortunately). I'm sure there's plenty of assumptions wrapped up in these regulations around estimated abode longevity, energy pricing over that period, etc. But as to multiple water sources into abodes, I haven't seen much formal work on it. I think the idea gets touted in London periodically - it'd be a nice solution to the dual problems of high water table and (surprisingly) occasional potable water shortages. But retrofitting this to an existing, massive, badly planned metropolis would be a nightmare.