Restrooms That Recapture Water And Waste

At Georgia Tech, green restrooms inside a new campus building include composting toilets.

By Anne Cosgrove
From the December 2019 Issue

Georgia Tech
The Kendeda Fund and Georgia Tech intend for this campus facility to achieve Living Building Challenge 3.1 certification. (Photo: Jonathan Hillyer)

At the Georgia Tech campus in Atlanta, construction of The Kendeda Building for Innovative Sustainable Design was completed this past fall. With classes set to begin in the 37,000 square foot facility in January 2020, this green building was primarily funded through a $30 million grant from The Kendeda Fund, a private family foundation based in Atlanta that focuses on community-driven solutions. The new campus building houses two 64-person classrooms, two 24-person class labs, two 16-person class labs, a 16-person conference room, makerspace, an auditorium, a rooftop apiary and pollinator garden, and office space for co-located programs. The building has been designed and constructed to achieve Living Building Challenge 3.1 certification (meaning that it gives back more to the environment than it takes through its construction and operation).

Early on in the design process, the project team made the decision to focus on water consumption in the building. As part of the sustainability focus for the building and Georgia Tech, the facility is designed to annually collect more water than it uses. Conventional flush toilets, known to be heavy water consumers in buildings were bypassed. In their place, a bank of composters in the building’s basement accepts waste from foam flush toilets and waterless urinals. These foam flush toilets use a few ounces of water per flush, and the composters transform human waste into material that will enrich soils in the surrounding landscape.

Water from the sinks, showers, and drains is treated and infiltrated on-site. A constructed wetland, filled with native plants and dedicated to demonstrating the power of nature to create clean water, is situated at the entrance of The Kendeda Building. This wetland filters graywater before it is infiltrated back to the groundwater through a drainfield located on the lower part of the site.

According to the building design documents and project team analysis, when the building is at full capacity, 13% of its total water usage is expected to be used for creating the foam to flush toilets (0.04 gallons per flush (GPF)). This is compared to 77% of water usage going to toilet flushing in a traditional building, using 1.28 GPF.

There are six restrooms throughout the building—on each of the two floors, there is a men’s, women’s, and gender inclusive restroom. The family restrooms contain a shower. There are 12 foam flush toilets, four waterless urinals, and 10 low-flow sinks.

Q&A On Green Restrooms

Facility Executive asked the Georgia Tech facilities management team about the restrooms, particularly the composting toilets in the building.

For the Net Positive Water Cycle pursued for Living Building Challenge certification, water traveling in and out of the restrooms is part of a closed loop. How do maintenance practices differ from “traditional” buildings?

The operation of The Kendeda Building restrooms is very different from traditional, commercial restrooms as the building’s wastewater is not connected to the sewer system. To be net positive in water use, we have to assure at least 95% of water captured on-site actually stays on-site. We accomplish this by using all graywater (e.g., water from sink drains, shower drains, and floor drains) for site irrigation and groundwater recharge. All condensate from the HVAC systems and rainwater is also captured. The building’s blackwater waste is captured in a leachate tank, so any nutrients that remain can be extracted and repurposed as non-edible fertilizer at an off-site facility. Leachate removal is handled through a third-party vendor.

Do cleaning and maintenance practices for the foam flush toilets differ from traditional water flushing toilets? What training, if any, has been necessary?

The cleaning practices inside of the restroom are very similar to traditional restroom facilities. There is a foam solution that sits inside of the toilet tank area and must be refilled approximately every 4-6 weeks. Clivus [of Lawrence, MA] is the manufacturer of the toilet and graywater system, and they have been contracted to manage all maintenance needs for the composting toilet system. This includes raking of the waste pile and maintenance of the sump pumps.Georgia Tech

The primary training needed is for users. Because foam flush toilets are uncommon, the toilet’s flush process can be confusing for the typical restroom visitor. In The Kendeda Building, the automatic foam flush toilets start producing foam when triggered by a motion detection device in the stall. This means that the flush process is automatic; the user has nothing to do with the flushing process once they enter into a stall. However, since there is no traditional “flush” sound to indicate the process is complete, it can be confusing. We’ve placed educational signs in the restrooms to help users navigate this unfamiliar experience.

The Kendeda Building
Each of the six restrooms in The Kendeda Building features foam flush toilets and low-flow sinks. The composting toilet system requires the separation of liquids and solids. The black tanks shown above store the liquids from toilets (blackwater). The system uses aerobic mesophilic decomposition to slowly break down solids into stable compounds. (Photos: Georgia Tech Facilities Management)

Please describe the procedure for removing solids from composting units. How often? Who performs this task? What equipment is used?

Solids that enter into the composter have to go through a very long decomposition process. This process can take years to complete. Once the material has completely decomposed, it will form a usable, “non-edible” fertilizer. (The fertilizer will not be used on anything grown for human consumption.) The leachate is removed by the septic vendor hired by Georgia Tech. That vendor has to provide us a manifest from a local processing site located in the city of Cartersville. They will handle all the nutrient separation and reintroduction of cleaned water back into the water system.

Are there any lessons learned thus far in the restrooms operations and maintenance in this new building?

According to Marlon Ellis, area maintenance manager for The Kendeda Building, teaching users about the foam flush toilets will be important. “Until these toilets become more common, the user will expect a common, water-filled toilet,” says Ellis. “There’s no standing water in the toilet, nor do we have the force of water entering the toilet bowl, so these toilets can only handle human waste and tissue. Other objects discarded in the toilet will not flow through the drain. Educational signage is a must for these restrooms.”

For maintenance, Ellis notes, “The composter system maintenance is fairly common to any maintenance facility. There is a sump pump inside the composter that requires routine maintenance, but that’s it. The system is very efficient and saves money on operation and maintenance.”

Project Team: The Kendeda Building For Innovative Sustainable Design

The Kendeda Building For Innovative Sustainable Design was designed by Lord Aeck Sargent, with subcontractors Newcomb & Boyd and Biohabitats leading on the integrated water system (the Net Positive Water Cycle). A diagram of the facility’s system can be found online at:

  • Architects: Lord Aeck Sargent and The Miller Hull Partnership
  • Builder: Skanska USA
  • Contributing Teams: PAE (mechanical, electrical, plumbing engineering), Newcomb & Boyd (mechanical, electrical, plumbing), Biohabitats (graywater systems), Long Engineering (civil engineering), Uzun+Case (structural engineering), Andropogon (landscape)
  • Permitting of water systems through Jacobs/CH2M

Cosgrove is Editor-in-Chief of Facility Executive magazine. To read more about The Kendeda Building for Innovative Sustainable Design, visit the Georgia Tech website.

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