WASTE-FREE WASTE

Japanese studio Tono Mirai Architects has used repurposed soil and wood to create Toiletowa, a curving structure in Saitama prefecture containing a public toilet that reuses wastewater. Located in a park in the town of Miyoshi, the building has a wooden frame covered with rammed earth made with soil sourced from construction sites and mixed with hydrated lime.

Tono Mirai Architects aimed to create a building that exemplifies waste-free construction, working with engineering firm IS Engineering and industrial waste treatment company Ishizaka Corp to develop its rammed-earth walls. The material covers the wooden frames of the two curving walls that enclose the public toilet, which is topped by a gently curving timber roof with skylights.

"A mixture of gypsum board and soil brought to Ishizaka Corp from demolished homes by house builders were separated and purified at the company's factory," studio founder Tono Mirai explained. "Until now, it had only been used as a roadbed material for pavement, but this is the first time it has been used as a building material."

The majority of the timber elements in the two structures are made from reclaimed wood, and the foundations are made from crushed stone instead of concrete. The basins and toilet bowls are also made from recycled wood chips.

"Most of the building is made from recycled materials and materials that return to the earth without using concrete," said Mirai. "More than just a toilet, it was built as an environmental education space that recycles industrial waste and serves as a model for a future waste-free, recycling-oriented society."

Neighbouring the toilet is a semicircular timber structure containing wastewater tanks, designed to display how water is circulated and reused for watering crops in the surrounding gardens.