Behavioral economics and the design of a dual‐flush toilet

Dual‐flush toilets, which use a high‐volume flush for solid waste and a lower‐volume flush for liquid waste, can reduce water consumption. Behavioral economics was used to analyze the design of the dual‐flush mechanism for the Sloan Uppercut® toilet. The default option, pushing the handle down, results in a large flush. Because Americans have been “conditioned” to push a toilet handle down, it was expected that most users would push it down out of habit. A field experiment measuring up versus down flushes in eight women's toilets in a municipal building confirmed this expectation. Although Sloan predicted a 2:1 urination‐to‐defecation ratio, the observed ratio during the control period was 1:4, i.e. the ratio was the opposite of what would occur if people used the toilets correctly. Adding signage to each stall only increased the ratio to 2:5, emphasizing the importance of the default.