When it comes to water resources in the western U.S., most of the low-hanging fruit’s been picked. Although most of the West is a desert, cities were established and flourished where water supplies were plentiful and cheap. But with urbanization, power production, agriculture, industry, and the environment all competing for the same limited resource, “plentiful and cheap” is gradually being replaced by “scarce and expensive.”
There’s no sign that a federal policy will rein in demand for the remaining water that’s available. Conservation can only achieve so much. With demand beginning to outpace supply, water is destined to get more expensive and communities will be more susceptible to extended droughts. In fact, our ascent up the steeper part of the price curve has already begun.
The question is, how much more expensive and how soon?
Every community has its own price escalation curve, a function of its cost to secure more water and its rate of growth in demand. In other words, it’s a simple case of supply and demand. Large metropolitan areas like Los Angeles, San Francisco, and Las Vegas have already extended their reach well over 100 miles, at great expense, to secure more water. Reno, Nev., has a 40-mile straw to a groundwater basin north of the city.
Those options are increasingly limited and costly and are not available for every community. Identifying freshwater supplies to provide long-term reserves is even harder to find.
‘Treating’ the issue
A community’s available water supply is calculated using the historic assumption that water is fresh until it’s used. After one use it becomes wastewater, to be treated, diluted, and returned to the environment.
But over the last 25 years, significant advances in treatment technologies have gradually enabled some highly treated wastewater to be used again to grow both food and fodder, thereby offsetting the need for fresh water. But because this reclaimed water is perceived as being not quite fit for human consumption, its use is strictly regulated and requires investment in a completely separate “purple pipe” distribution system.
Ideally, treatment technology would advance to a point where the waste could be completely eliminated from the water. Carcinogens that are a byproduct of our industrialized society would be eliminated, pathogens inactivated, and that refreshed water could be used to directly or indirectly augment the existing potable water supply. The result: a very reliable new source and no purple pipe.
This is already happening in Southern California. In Orange County, treated effluent from the wastewater plant is being further treated via reverse osmosis (RO). Because even RO doesn’t eliminate all contaminants, the water is further treated with advanced oxidation before storage in the ground. When demand is high, this groundwater is pumped up to augment the potable water supply.
The trouble is that RO isn’t for all cities. It’s energy-intensive and expensive to build and operate.
Most importantly, it doesn’t eliminate the contaminants; it just separates them into two streams: clean (about 80%) and dirty (about 20%). The dirty stream is still lost for reuse; and unless your city is near an ocean, you need to dispose a far more problematic dirty stream.