I’ve lifted this comment out of the comment box on the second water privatization post. It’s from Ed Reid, one of my very knowledgeable colleagues and sometimes, but not often enough, co-authors. Over to Ed:
Water supply shortages tend not to be short term events. They may persist for months or even years, as is the case on the West Coast, and was the case in the Mid-Atlantic region until this Spring/Summer. Therefore, there is no need (and little justification) for any response that is shorter than a meter reading period. Even if meters are read quarterly. the water authority could announce that the rates were being raised as of a certain date, and long period consumption could be prorated for the current billing period. I understand that this penalizes even those who conserve during some portion of the first long billing period, but the cost of perfection is quite high while the cost of water is generally quite low. Any inequity could be largely reversed by reducing the rates at the same point in a later billing period, after the water supply problem was resolved.
Water meters, like gas meters are not electrified, in general, so peak period measurement is not possible with most current meters; and, as pointed out earlier, is really not necessary anyway.
Many communities provide the option of separate meters for lawn watering, which are typically billed at a lower rate because no sewer charge is included in the rate. In these cases, a separate and even higher rate could be assigned to consumption through these meters during droughts or other periods of limited water supply. These users would still get a benefit when water was plentiful, but would be further penalized when water was in short supply.
Some communities, such as the older sections of Phoenix, still provide flood irrigation from their canal systems. This is a horribly wasteful practice and probably should be discontinued, especially during periods of limited water availability.
As the population of the US increases, these problems will become much more severe and will require more creative solutions. Probably one of the first end uses to be curtailed will be electric power plant cooling water, which will be hard pressed to compete with human consumption and agriculture for limited water supplies. I would vote for banning grass and rose bushes in the desert next; if you want to live in the desert, live in the desert and leave “up North” up North.
If population trends in the US continue, we will be sharing our current fresh water resources among a population of ~500 million souls by ~2050. Many once-through cooling and once-through washing applications are unlikely to survive through that period.
Waste water cleanup and reuse is very common practice today. I don’t remember the source, but I have read that the drinking water in New Orleans, LA has been through ~11 toilets on its way to the tap. Not a pleasant thought, particularly if you happen to live in NOLA, but a modern day reality apparently.