G2RT - Generation 2 Reinvented Toilet

“Half the world needs a toilet. The other half needs a better one.”

Nine years after the Reinvent the Toilet Challenge, in 2020 the Gates Foundation commissioned Shannon Yee from the Georgia Tech Research Institute to pool the most promising technologies in order to develop a Generation 2 Reinvented Toilet (G2RT). Yee was free to assemble a team to advance the model to mass-production maturity within three years. Around seventy researchers from all over the world were invited to turn Bill Gates’s vision into reality more rapidly.

Through a competition presentation at a convention hotel in Atlanta, we managed to enter the program with a compelling design prototype. Once again, an attractive design model secured a long-term contract for us.

Shortly afterwards, we were given one of the three leading roles in the program. We took charge of designing the toilet, the vacuum flush system, the separation of solids and liquids, and the supervision of the field tests.

G2RT Laboratory Tests 2021

Georgia Tech Research Institute and Helbling Technik, Wil, Switzerland

G2RT is a modular platform that comprises a common filter technology for liquids and two different treatment technologies for solids. During development, we worked closely with the two other engineering teams and designed several variants for the toilet, the front end, in parallel with the treatment plant, the back end.

Our design team had a very steep learning curve, and we were soon running trials ourselves in our water laboratory to develop a special vacuum technology and provide fully functional prototypes with electronic control systems for testing.

The G2RT test campaign was divided into three phases, each involving testing of entire systems by the technology partners, while field tests were conducted on four systems. During the four years we worked on the project, we produced over twenty fully functional front-end systems.

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G2RT Field Tests 2020–2023

Birla Institute of Technology and Science (BITS Pilani), India, and University of KwaZulu-Natal (UKZN), South Africa

While the laboratory tests were run under controlled conditions, the field tests in India and South Africa took place under real-world conditions in households. The systems were adapted to reflect differing conditions of utilization: water for cleansing after use in India and toilet paper in South Africa.

The field test in households posed a major challenge for the technology partners and the on-site teams, as existing toilets had to be converted, the test systems kept running, and repaired quickly if required. Our design team often provided support for such repair measures via a video link, like a ground station assisting with repairs to a space station.

Assembling our front-end system in a garage at BITS Pilani University in Goa with the local team. Handover of the technologies, joint assembly, and training are important success factors for field tests. However, the choice of households selected was also crucial, along with residents’ willingness to use our G2RT model instead of their conventional toilets and provide information about the experience.

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The G2RT system was installed inside a typical family household in India.

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View through the kitchen of a household to the EOOS vacuum toilet. Here, the treatment plant (far right) is immediately adjacent to the building entrance. Its size and the level of noise from the treatment technologies deterred users and ultimately also potential partners in the industry.

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G2RT Future Design Vision 2023–2024

Gates Foundation, Georgia Tech Research Institute

At the end of the program, we were given a “real” design assignment. We were asked to reflect on how to design the G2RT technology so compactly that the entire toilet could fit into the bathroom—a future household appliance that only needs a power connection and otherwise functions completely independently of the water supply or sewage system.

By this point, our team was very familiar with the individual components in the treatment module and, with assistance from the other partners, developed a design study offering technical solutions that could also be produced on an industrial scale. Four extraordinarily detailed design models were made. They are now on display in museums, in the foyers of industry partners, and at the Georgia Institute of Technology in Atlanta. The models are also presented at United Nations conferences.

The fully enclosed version of our design study. This is what the toilet could look like as an industrially mass-produced model. Aesthetically, it would fit into the white goods segment, like washing machines and refrigerators.

Comparison of the size of the field test version of G2RT and the Future Design Vision. The individual components were scaled down and reconfigured in several design iterations.

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Side view of the design study. The drawer is used to empty any dried content that can be dumped.

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The short and long pipes of the filter system are visible in the cutaway side view. Dried feces are collected in a drawer. The vacuum toilet and the white washbasin were produced by Japanese manufacturer Lixil using 3D ceramic printing.

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The G2RT Future Design Vision vacuum toilet is one of the highlights of the exhibition A Better Way to Go: Toilets and the Future of Sanitation at the Gates Foundation Discovery Center.

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The inner workings of the high-tech toilet. The control circuit board is visible, as well as the vacuum separation system (cut open, showing the interior filter), a conveyor belt on which compressed feces dry, and, at the bottom, the disk dryer, in which filter residues from the liquid module evaporate.

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