According to Dr. Lynn Broaddus, President of Broadview Collaborative, Inc, and next year’s President of the Water Environment Federation, decentralized or distributed water and wastewater systems contribute to utility resilience in addressing climate change and a better solution for congested cities.
There is a wide application for a decentralized system from rainwater and stormwater capture to wastewater treatment.
Some leaders already see this as an opportunity. In contrast, some see it as a threat to the existing business model because there are many technical hurdles to overcome to avoid water contamination.
In an article from Asia Pacific Infrastructure, Dr. Broaddus shares why she thinks a decentralized water system can work in some situations.
Broaddus cites examples of US cities that have decentralized water systems. She says San Francisco places a high value on sustainable technologies and have developed codes, ordinances, and standard to progress their use.
The San Francisco’s Public Utilities Commission’s ‘Living Machine’ treats their wastewater onsite for non-potable using an engineered wetland system. Broaddus feels that rainwater treatment can also be part of the decentralized and distributed system, especially for people living in temperate climates and can collect rainwater from their roofs.
New York City is another leader in a decentralized water system. The city’s extensive wastewater system will make improvements costly and highly disruptive for residents, making a distributed approach the best way to grow without placing a lot of pressure on the existing system.
For example, several high-rise buildings in the Battery Park area of Lower Manhattan were permitted to have their onsite wastewater treatment systems in their basement. This development began in the early 2000s.
It all depends on the local context
For constrained cities like New York, decentralized and distributed systems can have a role, and re-use of non-potable water can have applications in buildings and technologies.
For smaller urban areas that are growing, putting a large plant is very expensive. Growth projections are hard to do and sometimes not realized, leaving cities with a costly system to pay, as is true with some US communities struggling through bankruptcies.
In such cases, some communities would be better off with scalable technologies that can be built as needed, which are more affordable and manageable solutions, according to Broaddus.
In rural areas that rely on septic systems and water to flush waste, water carries pollutants and spreads them. Using less water can make it easier to separate contaminants that could be used as fertilizer.
Bill and Melinda Gate Foundation is promoting research on waterless systems for developing countries. Still, this kind of technology can also be used in developed countries, especially in areas that are “sitting on bedrock.”
Roadmap to get there
In terms of quality, people can get the same experience from a home system as with a large and centralized system with a bonus of a better environmental footprint, Broaddus says.
“I am always surprised at the number of brilliant leaders in the water industry who predict that distributed technology is the way we need to go,” she says. There is not, as yet, a roadmap for how to get from this aspiration to implementation. “Our challenge right now is figuring out how to get there and creating the beginning of the pathway,” she added.
Opportunities for a decentralized water system
To address the growing population and water constraints in Austin, Texas, the city plans to capture and treat 100 million gallons of water per year by 2040 through its “Water Forward” plan.
Captured water will come from their onsite resources, including onsite sewage treatment, rainwater, and similar low-cost and easy-to-purify water sources. There is enthusiasm among developers and the community, but codes and oversights need to catch up with the plan.
Broaddus explains how a distributed or decentralized water systems can work better than centralized systems in some situations and cites examples of cities that are implementing it or plan to implement.
She says that decentralized systems that are thought to work only in developing countries lacking certain resources can also benefit developed countries.
With climate change adding pressures on resources, having a decentralized system can help communities manage their resources onsite and making them more climate-resilient.
But as with any potential solution, implementing decentralized and distributed systems comes with many infrastructure management challenges and perhaps some doubts from people who support the idea that having a centralized system is the path for growth.
But as Broaddus puts it, for the system to work would require a change of mindset.