Saving flush water with a new toilet coating

Researchers at Pennsylvania State University in the US developed a coating that could reduce toilet water consumption by half, saving billion litres of water every day.

Daily, more than 141 billion litres of water are used solely to flush toilets. A conventional toilet uses 6 litres per flush.

The new coating is a “robust, bioinspired, liquid sludge- and bacteria-repellent coating that can essentially make a toilet self-cleaning,” according to the researchers. Called liquid-entrenched smooth surface (LESS), the coating is a two-step spray that, amongst other applications, can be applied to a ceramic toilet bowl. The first spray consists of molecularly grafted polymers. When it dries, it grows molecules that look like little hairs, with a diameter of about 1,000,000 times thinner than a human’s.

The first layer already creates an extremely smooth layer, but the coating’s function is even more enhanced with another layer which essentially infuses a thin layer of lubricant around the nanoscopic hairs to make it even more slippery.

With the coating, toilets can effectively clean residue from inside the bowl and dispose of waste with only a fraction of the water previously needed, since nothing can stick to the material. The coating lasts for about 500 flushes in a conventional toilet before reapplication is needed.

The LESS coating only takes five minutes to apply and cure, and the coating repels bacteria, including ones that spread infectious diseases and unpleasant odours.

Photos: Pennsylvania State University / Wolfmann