For over a century in the developed world, water was treated as effectively unlimited, safe, and nearly free, a condition so stable it became invisible and unquestioned. That era is closing because climate volatility, population growth, and aging infrastructure now force water to be managed as a scarce, priced, and contested resource rather than an assumed background fact.
People ignore water almost completely as long as it is cheap, clean, and always flowing, giving it no thought and assigning it no value. This invisibility is itself a sign of abundance, but it leaves societies unprepared to think clearly about water the moment supply, quality, or cost breaks down.
Las Vegas, in the middle of a desert with minimal rainfall, returns and reuses almost all water used indoors: every drop that goes down a drain is treated and credited back to Lake Mead, so indoor use is essentially 'free' against its Colorado River allocation. The city therefore targets outdoor water, paying residents to rip out lawns, because that water evaporates and cannot be recaptured.
Treating all water to drinking-water purity and then flushing toilets, watering lawns, and cooling factories with it is a mismatch, since most uses do not require potable quality. Seeing water as a spectrum of grades, where lower-quality or recycled water is routed to lower-demand uses, reframes scarcity as largely a problem of misallocation rather than absolute shortage.