By Jim Lauria
Water scarcity is a growing challenge worldwide — even in countries graced with decent rainfall and a relatively robust system of dams and reservoirs. And it’s only going to get worse as populations and standards of living continue to increase.
We’ll find solutions by looking across the full spectrum of the colors of water. In his book Dry Run, Jerry Yudelson navigated his readers through a colorful world of gray water, black water, brown water and green water. Each of those colors tells us something about the condition of the water and its relative value — vital information in a world where every drop counts.
Increasingly, water is becoming what authors Maude Barlow and Tony Clarke called “blue gold.” A May 2000 Fortune magazine article predicted that water will be to the 21st century what oil was to the 20th — “the precious commodity that determines the wealth of nations.”
Talk about a shift in global power. In 1999, Terence Corcoran of Canada’s National Post newspaper predicted there would be an OPEC-style cartel of water-rich countries controlling the global price of water. His timeline might be off — he envisioned the rise of the cartel by 2010 — but time will tell if the concept takes form.
The world water economy will be prone to shakeup, especially as erratic weather induced by climate change amplifies flood and drought cycles, and may even shift global rain patterns. Today’s water-rich nations may find themselves watching their water bankbooks carefully. Poor, dry regions may find their fortunes further eroded, along with their landscapes, as dry spells last longer and longer.
The term “brown water” is familiar to urban planners and civil engineers as the descriptor for stormwater runoff. Often rich with sediment, it’s an accurate term, but probably undervalues the resource.
Brown water can be spun into gold through rainwater harvesting. Capturing rainwater isn’t a new concept — from ancient societies to modern Queenslander houses in Australia, stormwater has long been shunted to barrels or cisterns for future use.
Rainwater harvesting systems are maturing, and they are appearing in areas that may well have traditionally taken water for granted. From the roof-fed “rain gardens” of Portland, Ore., to the sophisticated rainwater capture system in New York City’s Bank of America building, green designers are viewing roof surfaces not just as a collection of tile, asphalt or metal sheets, but as a capture system for a valuable resource.
Rainwater needs little to no treatment for use in most irrigation systems — a few hours of settling or some modest filtration will do. As in the Bank of America system, it’s also a great resource for non-potable uses such as flushing toilets, as long as microbial growth is managed. (After all, this is water straight from the skies, run across broad, exposed surfaces. We’re working with an ecosystem — and it’s still brown.)
Looking to the future, brown may get even greener. Treating rainwater to drinking water standards requires less than half the kilowatt-hours it takes to produce desalinated water. Where water is scarce and energy expensive, that is an equation that can’t be ignored.
Gray Water Goes Green
Gray water — household wastewater from sinks, showers and laundry, but not from toilets — is another diamond in the rough. It’s easy enough to divert gray water to irrigation use and it’s already written into the International Plumbing Code, widely used in Europe and Australia, but as Oasis Design in California notes on its web site, regulations governing the use of gray water can vary widely among jurisdictions within the U.S.
Packaged systems for gray water treatment are becoming more common as homeowners and industrial water users increasingly recognize how much usable water flows down their drains. Gray water can’t be handled lightly — issues like backflow into potable systems and pathogen management need to be attended to carefully — but it’s a resource we shouldn’t overlook. Proponents estimate gray water re-use could reduce household water consumption by as much as 30 percent.
That turns gray water into green water — an environmentally beneficial use for a product most of us think of as waste.
The growing appreciation of water waste, and the availability of on-site treatment, can have significant benefits not only on local landscapes, but on municipal wastewater treatment plants. As populations grow, and regulations on residues in treated water multiply, those treatment facilities will be increasingly strained. Reducing the load on wastewater facilities and septic systems can add years to their functional life, while reducing the draw on potable water for landscaping and irrigation.
Some innovative designers are routing gray water to pre-warm incoming clean water on its way to the water heater, reducing energy for preparing the next gallon headed for the shower or sink. Those are clearly the shades of gray we need to be seeing.
In the Black
Black water — toilet water, sewage, wastewater containing fecal matter and urine — is one of society’s greatest challenges. Here’s where we see a sharp division between past and future.
In the past, black water management was an issue of disposal. A fast-running river used to suffice. Then we recognized the importance of wastewater treatment before discharge. Today, discharge is increasingly regulated by laws such as California’s Title 22, which requires very specific types of treatment before release to the environment. We can expect much more of that sort of regulation, and even stricter ones, as time goes on.
That’s where the future vision comes into play. Instead of fetid waste, we need to start recognizing black water for what it is — a source of nutrients, water and energy. It’s a resource, and we need to begin treating it like one.
Black water clearly presents challenges, not the least of which is its pathogen load. But we have the treatment and disinfection technologies to address that, as Singapore’s PUB has abundantly demonstrated with its NEWater system. Such “toilet-to-tap” projects invariably stir up opposition and disgust among voters, but we’re going to have to learn to get over it. And treated wastewater doesn’t necessarily need to go all the way back to the tap: there are plenty of agricultural and industrial uses for it.
Treating black water will require us to tune into combinations of filtration, separation and disinfection processes to make the process more efficient. We’ll need to adopt ways to mine the value of black water’s organic solids, whether it’s for their value as soil amendments and fertilizer, or tapping their Btu value through biogas, fermentation heat or other means. We’ll need to be smart, to break up black water into its various components and unlock the value of each in a logical, profitable way.
Not surprisingly, technologically advanced nations with water scarcity issues will guide the way (though houses I’ve seen in China with manure pits and biodigesters are modest-but-advanced models themselves). Where pollution is a challenge, the pressure will grow to divert black water to other uses. And if water issues don’t force our hand, energy costs might. Energy costs are rising faster than water utility revenues, so cities and contractors will be looking for a new paradigm.
As Cervantes’ character Byron said 400 years ago in the classic Don Juan, “’til taught by pain, men really know not what water is worth.”
Back to Blue
The instinctive aversion to black water has very valid roots. In The Blue Death, Robert Morris chronicles milestones in epidemiology in a non-fiction book that crackles with the excitement of television’s CSI — a real-life whodunit. His detailed description of Dr. John Snow’s demonstration of how cholera spread through London’s slums, culminating in removing the handle from a well pump that was quite literally the font of the epidemic, should be required reading within the water community.
Morris’ book winds through the contributions of great thinkers including Edwin Chadwick, Henry Whitehead, Louis Pasteur and Robert Koch, each a pioneer in understanding water and teaching us how to make it truly blue. He ends with a call for comprehensive clean-water policies, from mandating multiple barriers for pathogen control to replacing our crumbling infrastructure.
With clean, blue water — part of a continuum across the spectrum from green to brown to gray to black — we will be able to face future demands and coming disruptions in the water supply. If we see water for all its colors, we can capture more of its true value and find a pot of gold at the end of that rainbow.
About The Author
Jim Lauria is a water technology executive with a Bachelor of Chemical Engineering degree from Manhattan College. He has over 20 years of global experience as a senior executive in the water treatment industry. Jim is a marketing executive, engineer, writer, blogger, and water evangelist. He is a frequent speaker at water industry conferences and has published over 50 technical articles in water trade publications. He can be contacted at (805) 410-2674 or email@example.com.