Water Infrastructure for the Future
What is Decentralization?
"We’re at a point where drought, an aging infrastructure and a host of other problems are leading us to examine the future sustainability of our water supply. Interim solutions, like water conservation and retrofits to treatment systems, can help, but eventually we’ll need a major upgrade."
-UC Berkeley urban-water expert David Sedlak
Ways of supplying water can be characterized along two axes. One deals with the infrastructure, which can be centralized or decentralized. The other deals with the water which is used: either freshwater only, for a single use; or alternative sources of water.
Central Infrastructure
Decentralized Infrastructure
Prevailing in OECD Countries.
Single quality water is provided by central infrastructures.
Waterborne sewerage is centrally collected and treated in a plant usually located at the outskirt of the urban area.
Not common in OECD urban areas
Relies on point of use resources.
Connections to central infrastructure may be needed to ensure reliable sourcing
Freshwater Only
In use in some contexts
Treated or untreated rain and grey water is sent back to the city where it is used again.
The System requires an additional network and energy is used to transport wastewater and reclaimed water.
Widespread in Specific contexts.
Water is produced and treated locally
(on the point of use).
Treated or untreated rain and grey water is used for (usually non potable) uses.
Alternative Sources of Water
Centralized vs Decentralized
The main difference between centralized and decentralized water recycling systems is where the water is treated and reused. In a centralized system, water is collected from many sources, sent to a large treatment plant, then distributed for reuse. An example of this is the huge water recycling plant in Orange County. In a decentralized system, water is treated and reused right at the source. A system like this can be used for small communities, apartment complexes, and even a single household.
