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A doctoral student at San Diego State University has designed a low-cost, low-water toilet that could benefit homeless, rural and refugee populations who often lack regular, safe access to restrooms. 

“America is the epitome of the flush and forget system,” said Lilith Astete Vasquez, an environmental engineering doctoral student at SDSU and lead author of a recent Scientific Reports paper demonstrating the benefits of low-water toilets she designed.

It is common practice in most American restrooms to use large amounts of water to flush away human waste. But that’s not possible in communities where water is scarce due to drought or contamination, increasing the risk of disease.

To solve the need for sanitary toilets that use minimal water, Astete Vasquez took inspiration from an experience that her advisor, engineering professor Natalie Mladenov, encountered in rural Botswana. While studying polluted rivers, Mlandenov came across a toilet with an underground reservoir that didn’t smell and could be flushed with minimal water.

Mladenov and Astete Vasquez designed an experiment to understand how this toilet could so successfully decompose waste. In the lab, they tested the role of bacteria that don’t need oxygen to break down organic matter, as well as a simple mixing system to increase the effectiveness of the bacteria.

“Lily’s work is fantastic in that it’s simulating real-world scenarios that are important for developing and developed world situations,” Mladenov said.

Based on the results of her study, Astete Vasquez is currently in the process of patenting a low-water mixing device that can be retrofitted into existing rural septic systems. Once patented, she plans to install some in national parks and in mobile hygiene trailers operated by ThinkDignity, a local non-profit organization that serves San Diego’s homeless population.

Chris Jennewein is Editor & Publisher of Times of San Diego.