Every day, more than 141 billion liters of water are used just to flush toilets. The new method dramatically reduces the amount of water needed to flush a conventional toilet, which usually requires six liters.

“Our team has developed a robust bio-inspired, liquid, sludge-, and bacteria-repellent coating that can essentially make a toilet self-cleaning,” says Tak-Sing Wong, professor of engineering and associate professor of mechanical engineering and biomedical engineering at Penn State.

Testing the self-cleaning toilets

Jing Wang, a doctoral graduate from Wong’s lab, co-developed the liquid-entrenched smooth surface (LESS) coating, which is a two-step spray that, among other applications, can be applied to a ceramic toilet bowl. The first spray, created from molecularly grafted polymers, is the initial step in building an extremely smooth and liquid-repellent foundation.

“When it dries, the first spray grows molecules that look like little hairs, with a diameter of about 1,000,000 times thinner than a human’s,” Wang says.

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