The bricks are made using urea — a chemical found naturally in urine and also synthesized around the world to make fertilizer. The process of growing bricks from urea has been tested in the United States with synthetic solutions, but the new brick uses real human urine for the first time, the researchers said.

“We literally pee this away every day and flush it through the sewer networks,” said Dyllon Randall, a senior lecturer at the University of Cape Town’s civil engineering department who is part of the team that developed the brick. “Why not recover this instead and make multiple products?”