David L. Sedlak, Engineering Professor at Berkeley, Deputy Director of the Berkeley Water Center, and 2014 winner of the Clarke Prize for excellence in water research, has written a book about water issues: Water 4.0. He rejects the usual structure of this kind of book:
About twenty years ago, when I started getting interested in these issues, I encountered a problem: the books on water intended for a general audience were too general, with large sections dedicated to disparate issues like wasteful agricultural water use, destruction of aquatic habitat, and the water and sanitation needs in the developing world.
Whether you like Water 4.0 may depend on whether you agree those topics should be minimized. The omissions do at least leave room for major sections on the history of water management: Roman aqueducts (Water 1.0), medieval “buckets” (2.0), and modern drinking water and sewage infrastructure (3.0). (You gotta give Sedlak credit for expecting a “general audience” to read technical sections on biofilms, alum precipitates, Imhoff tanks, combined sewer overflows, sanitary sewer overflows, chlorination byproducts, activated carbon, EPA standards for trihalomethanes, ozonation, and the Streeter-Phelps dissolved oxygen sag curve.)
Water 4.0 argues that the current centralized system of water supply and wastewater treatment is breaking down. It is not meeting user needs, is becoming too costly, and may not be providing safe drinking water. Sedlak proposes specific solutions to these problems. His overall goal:
To wean cities from centralized water systems and all of their associated problems, we might simply have to find a way to make decentralized water supply and treatment practical at higher population densities. It’s quite likely that we’ll never break free of centralized water and sewer systems in the middle of our most densely populated cities, but a society equipped with the latest innovations in information technology, biotechnology, and materials science should be able to improve on the groundwater wells, septic tanks, and unlined ditches that served our rural communities so well during the twentieth century.
Cost is a problem, though:
Under these circumstances, decentralized water reuse can be achieved by building a network of tiny wastewater treatment plants in the basements of homes and apartment buildings. Running a network of distributed membrane bioreactors would cost around $3.40 per thousand liters ($13 per thousand gallons) of water produced. That’s about five times more than the current cost of water reuse or desalination.
That cost per thousand gallons might come down with better technology. Wastewater reuse, gray water utilization, drastically cutting lawn irrigation, and decentralized water alternatives “might reduce a city’s potable water consumption by as much as 50 to 75 percent.” Big reductions in water use too should reduce the total cost of water services. (Also true for central systems, though.)
Changing to Water 4.0 would mean many transitions, perhaps not all desirable. This is where the tight focus of the book prevents full understanding of other compelling issues. How does one persuade people to give up residential irrigation? Do mortgage interest and agricultural subsidies stand in the way of the transition? What are the implications for environmental justice? Would lakes, rivers, and springs have as much water flowing to them and would they be cleaner or dirtier in Water 4.0? Would the emission of greenhouse gases in a decentralized system be larger or smaller? Would the new group of decentralized water home gurus tend to be only those with extra money lying around? Would these homeowners lose their interest in centrally provided services for others less fortunate or less interested in advanced technology?
There may be particular relevance to Florida. Keeping more water onsite is usually good for water quality in this state. If you can catch some water and reuse it in the home or on the landscape, so much the better. However, the state Legislature will not even require septic tanks to be regularly inspected, so it is hard to have confidence in proper management of a multiplicity of more complex wastewater systems. I also wonder, in light of how many Floridians install home water filters and buy bottled water for supposed “health” reasons, whether many people are willing to drink water coming off their roof.
Nonetheless, Water 4.0 is a creative and thought-provoking example of approaches to water consistent with the ideas of another recent book, “A Twenty-First Century U.S. Water Policy.” Some community in Florida should give water decentralization a big push and see how successful it turns out to be.