With their big-pipe centralized water services, urban areas have historically provided limited opportunities for onsite professionals. That was then, as they say. Expanding populations and warmer temperatures driven by climate change are forcing a new emphasis on water reuse in urban areas, and onsite water recycling systems are popping up there, too.

Some urban recycling systems are extremely complicated, while others are simple, and there is a need for qualified onsite operators, says a report published by the Pacific Institute in Oakland, California. The report is titled The Untapped Potential of California’s Urban Water Supply: Water Efficiency, Water Reuse and Stormwater Capture.

“Pacific Institute has a long history of working on urban efficiency and reuse, predominantly in California and the western U.S., although we’re doing more national and global work,” says Cora Snyder, one of three people who wrote the report. She is a senior researcher at the institute, holds a bachelor’s degree in environmental studies and a master’s degree in environmental science and management, and her job is to work with companies, governments and nonprofit organizations to advance water sustainability.

“This project really started in Silicon Valley, looking at a lot of the large tech campus developments. Several of those have these onsite systems,” she says.

A few recycling systems serve tall buildings on confined city lots, she says. “I think where it makes the most sense to do this kind of onsite system is at a larger property that has outdoor landscaping that requires irrigation.”

NEW DEVELOPMENTS

“Office campuses make a lot of sense because you have a lot of nonpotable water demand. You’ve got the outdoor irrigation. You’ve got cooling. You’ve got flushing. Up to 90% of a building’s water demands can be met with onsite reuse,” she says.

Projects cited in the report were for nonpotable use. Potable reuse was beyond the scope of the report, Snyder says.

Some startup companies are offering solutions for urban onsite recycling, Snyder says. “For the most part this is tried and true water recycling technology that has existed for decades,” she says. “I do think the scaling down — how you make it cost-effective at a smaller scale than a municipal water recycling plant — is a question.”

Some of the urban systems recycle blackwater, she says. A system at the Google campus in Mountain View, California, uses both natural wetland filtration and reverse osmosis to reuse graywater, she says.

The institute report didn’t include a cost-benefit analysis, but the authors did look at what drives reuse investments. “I would say there are long-term financial benefits,” Snyder says. “I think most of these companies are doing their own internal analyses, and they’re not going to invest if it doesn’t make financial sense.”

Other factors push onsite recycling, she adds: corporate sustainability goals; public perception, especially in California where a long drought makes people watch how carefully businesses use water; and in Silicon Valley the culture of innovation, the willingness to try new things and curiosity to see how far technologies can be pushed.

In the San Francisco Bay area there is also a “green premium,” she says, making real estate more valuable if it has certifications for environmental sustainability.

MULTIPLE BENEFITS

A number of projects are highlighted in the report. “What we were really looking for was different elements of onsite systems that we could highlight,” Snyder says.

For example, she says, one in New York City had a heat-recovery element. The Google project includes publicly accessible outdoor space. Another used a public-private partnership.

Personally, Snyder says, she liked a couple of projects. In San Francisco the Exploratorium — a science museum that emphasizes hands-on experiences to teach science concepts — wraps its onsite recycling project into its education. She likes the New York City project for two reasons. First, it’s a high-rise residential development, and reuse is less common in those.

“Then the heat-recovery element was important because these systems are energy-intensive, and that demonstrated a way to use other resources coming out of an onsite system that could help offset that energy requirement. I like that multi-benefit approach.”

The New York City project is at the Solaire, a luxury apartment building near the southern tip of Manhattan and the city’s financial district. Its onsite system treats 25,000 gpd used for flushing toilets, irrigating landscaping, and making up cooling tower water lost to evaporation, says the Pacific Institute report.

Recycling cuts the building’s potable water demand from the city water system by 50%. Heat extracted from the wastewater is used to preheat water heading into the building’s hot-water system. The website for the building says wastewater is filtered through seven layers of media, including activated carbon, that remove particles down to 10 microns. The website also says this onsite system was the first in the nation to be built inside a multi-family residential building.

CHALLENGES

One current challenge to doing these projects is permitting and regulation, she says.

“Because this is just emerging, and every system is a little different, there’s not really a standardized approach yet,” Snyder says. That’s the goal of rules now being developed by the state of California, she adds. Rules already issued by the state say permitting for recycling systems will be done by local authorities using state standards, she says.

Another challenge is finding qualified people to operate and maintain these systems, Snyder says. The National Blue Ribbon Commission for Onsite Non-Potable Water Systems (part of the U.S. Water Alliance) is doing some workforce development for this, she adds.

Another barrier is the cost of water.

“I think companies are looking ahead and anticipating rising water costs, but right now water is relatively cheap,” Snyder says, “so it can be difficult to make the financial case for investment in these systems, even though companies are looking at drought conditions, looking at increasing water scarcity conditions, and feeling like this is the right thing to do.”

Two key ideas about onsite recycling resonate with the general public, she says. One is circularity, the notion of reusing a resource many times. The other is decentralized resource use, like solar panels on house roofs.

“Folks can have resources like energy and water that they can produce at their own sites, whether it’s an office building, or a household, or a campus development,” she says.

CONTINUING NEED

California had a very wet winter that dumped many feet of snow and rain and nearly eliminated the state’s three-year drought.

“I will say every time we have a wet winter there is a little bit of collective amnesia about the water scarcity challenges we face, but I do see increasing recognition that we know one wet year is not going to solve the problem,” Snyder says.

Given the need for alternative water sources, and with climate change a particular concern in the western United States, it’s likely both onsite and large-scale water recycling will increase, Snyder says.

Increased use of onsite treatment may also affect the relationship between the onsite and municipal treatment communities, she says.

“For water utilities, these kinds of systems can present a challenge because it requires a new way of thinking. Generally speaking, for the last 100 years or so, we’ve been building, designing and operating water systems that are centralized and linear. They’re big water infrastructure systems that get water to one place, you use it once, and then you discharge it. Onsite water reuse totally disrupts that model, but it’s a model that needs disrupting given what we’re seeing with increasing water challenges.”