WC Archive

Traditional water engineering (sometimes called the "hard path") focuses on centralized supply and infrastructure, emphasizing meeting water needs by simply supplying more water. This path worked, and worked relatively well, in much of the developed world, but hasn't done as well in the developing world -- 1.1 billion people lack access to clean and safe drinking water, and 2.6 billion lack access to adequate sanitation. Global warming-induced climate disruption will exacerbate problems that arise in centralized water systems, and conflicts over the need to control water supplies are likely to grow over the coming decades.

In contrast to the hard path is the "soft path," emphasizing the provision of water services, a mix of centralization and decentralization, and improvements to the efficiency and productivity of use. "Water services" in this context means what people do with the water they need. Drinking water needs can only be met by clean water, but sanitation needs (for example) may have other alternatives. By thinking of water uses as services, planners can look at a greater range of alternative solutions.

The cornerstone of the soft path, however, is rethinking the concept of supply. For hard path engineers, water supply means just that -- the reservoirs, lakes, rivers and groundwater from which urban water is pulled. Soft path adds to that list more exotic sources such as desalination, smaller "microsources" such as rainwater harvesting, and a reduction in the need for fresh water through reclamation, reuse/recycling and efficiency-based conservation. While traditional water planners don't list conservation and water recycling under supply (a fact that led to an amusing moment with Dana Haasz from SF Water arguing that her own department-provided slide was wrong), soft pathers do -- anything that helps users meet their water needs counts as supply.

Efficiency and the cultivation of an efficiency mindset came up very frequently across the talks, and often as an explicit parallel to the energy context. As with energy generation and consumption, there's plenty of room for improvements in the efficiency of water production and use -- and, as with energy, there's already a trend towards better efficiency underway. Some of the improvements can come from infrastructure repairs -- aging pipes and conduits can waste a significant percentage of water in transit. Others can come from directly changing how water is used -- low flow toilets and showerheads, drip irrigation, and the like. Still other improvements can come from addressing the use of water in industrial production techniques.

The latter has already shown its value; according to Peter Gleick from Pacific Institute, the semiconductor industry is an excellent example of how efficiency can improve. In 1990, making semiconductor chips required 30 gallons of water per square inch; by 2005, that was down to 6 gallons per square inch; by 2009, the industry estimates it will be down to an average of 2 gallons of water per square inch. The reduction in water requirements has complementary effects in the environmental arena, as less waste water is produced.

That's an example of an economy of scope. Pacific Institute's Gary Wolff defines it this way:

A "scale economy" exists when a bigger facility will be less expensive per unit.

A "scope economy" exists when one facility delivers two services at a lower cost than two facilities, each delivering one service.

In other words, an economy of scope arises when a single change has benefits across multiple sectors. Wolff also calls these "co-benefits," and gave as an example rainwater harvesting, which both improves the water supply and reduces the need for runoff management.

As a service moves from a few large centralized facilities to many smaller, decentralized facilities, opportunities for economies of scale fall off -- but opportunities for economies of scope can expand. We can see examples of this outside of the water context, as well: "Plug-In Hybrids" or "Gas Optional Hybrids" not only provide high-efficiency transportation, they can provide home power when plugged-in in the garage, reducing grid demand during the day (and then recharging at night, when overall demand and costs are lower).

Other interesting bits from the talks:

Around 1980, the connection between water demand and economic growth "broke," and the trend across the developed world has been flat or even reduced per-capita use in the years subsequent. In California, the state as a whole actually used less water in 2000 than it did in 1980. Some of that is attributed to changing industries (chips take less water than steel), but most to improved efficiency. As a result of this, a number of planners around the world are starting to reconsider their long-range demand projections.

One of the reactions to climate change from water planners and engineers is the increased use of "portfolio theory" and financial management software as tools for handling the increased uncertainties of water supplies and use.

San Francisco just completed a 25 year water plan, taking into account demographics, projected supplies, changes to the economy, etc. (but possibly absent -- global warming). Under that plan, the city is expected to increase in population by about 10%, while reducing its overall water use by 17%.

The energy world is miles ahead of the water industries in thinking about efficiency. One energy technique increasingly being adopted by people in the water field: labels. Energy consumption labeling turned out to be one of the best ways to improve appliance efficiency, as consumers could see and compare power use -- appliance efficiency increased dramatically as a result. Similar labels for water efficiency could have a similar effect. Interestingly, such labels appear to be used in the developing world much more than in the West, at least for now.