Materials

Water-saving toilet bowl coating gives waste the slip

Water-saving toilet bowl coati...
According to Penn State, a typical toilet uses 6 liters (1.6 US gal) of water per flush
According to Penn State, a typical toilet uses 6 liters (1.6 US gal) of water per flush
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According to Penn State, a typical toilet uses 6 liters (1.6 US gal) of water per flush
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According to Penn State, a typical toilet uses 6 liters (1.6 US gal) of water per flush

Given the current worldwide push for water conservation, it's certainly ironic that people are still flushing great quantities of the stuff down their toilets. They may soon be using up to 50 percent less, however, thanks to a slippery new toilet bowl coating.

Developed by scientists at Pennsylvania State University, the liquid-entrenched smooth surface (LESS) coating is applied to standard ceramic toilet bowls in two steps.

First, a solution of molecularly-grafted polymers is sprayed on. It quickly dries, growing into a "forest" of tiny hair-like molecules – each one has a diameter about one one-millionth that of a human hair.

Although that initial treatment already leaves the inside of the bowl quite slippery, a second spray is subsequently applied, infusing a thin layer of lubricant around the hairy molecules. The whole two-step process takes less than five minutes, and the resulting coating should be good for about 500 flushes before another application of lubricant is required.

In lab tests, synthetic fecal matter slid right off the inside of a LESS-treated toilet bowl. This meant that only "a fraction" of the usual amount of water was needed in order to get that matter out of the bowl and down the drain.

As an added benefit, it was also found that the coating repelled the bacteria that can spread disease or cause unpleasant odors. With these features in mind, it is now hoped that the technology could not only make flush toilets more water-efficient, but that it could also allow waterless toilets (which are widely-used in many parts of the world) to be more hygienic and less objectionable to users.

The coating is being commercialized by spotLESS Materials, a Penn State startup. A paper on the research, which is being led by Prof. Tak-Sing Wong, was recently published in the journal Nature Sustainability.

Source: Penn State

6 comments
paul314
So can it be applied under home toilet conditions?
Catweazle
This may well cause problems further down the line. I believe that in Germany a problem has arisen due to the reduction in volume of toilet flushing due to there being insufficient volume of water to keep the plumbing clear, as the gradients had been calculated to function with a particular minimum flow volume.
Sirmike
Completely agree with Catweazle. I live in a first floor apartment and when the second floor apartment flushes it blocks the pipes so that either my toilet won't flush and has to be plunged or it just takes a time for it (even just pee) to seep away. They have a low flush toilet, I have a dual flush. The problem is really that the pipe gradients were for the 1960's and now they haven't sufficient drop for the small amounts of water used in low flush toilets. This is far more a problem to be solved than getting stuff out of the bowl.
Douglas Rogers
This is worthwhile but it is not a huge use of water. Most of the water is used for irrigation in arid lands.
ljaques
It's too bad that the treatment isn't permanent, as home treatment would never be possible. 500 flushes in a large family would be a matter of weeks, and just months for singles. Just to set it up to apply would open the sewer air into the home, and people won't put up with that willingly. Plumbing pipe drain slopes are also too shallow for this to avoid problems, as Catweazle stated.
Bruce Anderson
It is one thing to slip off a flat surface, and quite another to travel through a curved channel. Renewing the coating means it will wear, and the assumption is that it will not work nearly so well once 500 flushes are met. And the cost to apply and re-apply would be nice to know. And paul314 raises a VERY interesting question.