It appears that development of a new paradigm for water systems is both necessary and likely. The old paradigm and the emerging paradigm are broadly characterized below. These are simplifications of course, and many systems are in transition, but the rough differences in approach are instructive. The Emerging Paradigm Human waste is a nuisance. It is to be disposed of after the minimum required treatment to reduce its harmful properties.
Human waste is a resource.
It should be captured and processed effectively, and put to use nourishing land and crops. Stormwater is a nuisance. Convey stormwater away from developed areas as rapidly as possible. Stormwater is a resource. Harvest stormwater as a water supply, and retain or infiltrate it to support aquifers, waterways, and vegetation.