This video of a McDonald's bathroom sink with an integrated smartphone cleaner went viral:

That UV-light-containing slot is just part of the story. The system was devised by a Japanese company called WOTA, which is dedicated to solving the world's water crisis by devising structural solutions.

The largest problem the company sees is that humans waste a lot of water. We wash food, our bodies, our clothes, our cars, and the run-off goes down the drain. All of those gallons/liters of water are essentially single-use. What if it could be cleaned and recirculated, as if we were astronauts?

To address this WOTA invented the WOTA BOX, a portable water recycling plant:

It uses six filters, UV lighting and chlorine disinfection, along with sensors and an AI-driven monitoring system, that filters out more than 99.9999% of viruses and bacteria, the company says. The filthiest among us could take a shower and the greywater, filtered through the WOTA BOX, would emerge clean enough for us to drink (it complies with the WHO Guidelines for Drinking Water Quality). It loses just a tad over 1% of water with each cycle; seen another way, it conserves over 98% of water each time.

To put it into use, the company has created an Outdoor Shower Kit meant for disaster relief. With the high water recycling rates, this means relief facilities require just a fraction of the water that would ordinarily need to be trucked, piped or airlifted in.

To make the technology more visible in everyday situations, the company also developed WOSH. This is a freestanding portable handwashing station, based on a 205-liter drum, that doesn't require any plumbing, but does require electricity.

It can be placed anywhere—in a store, a train station, a parking lot, etc.—where there's a nearby plug.

Fill it with water, and the same system that powers the WOTA BOX recycles over 98% of it. Twenty liters of water, the company writes, would thus last for 500 hand-washing cycles.

The company added some tech gimmicks to increase the visibility of, and the memory of using, the WOSH. A ring of light encircles the sink basin. Once you start washing your hands, the light ring visually counts down for the recommended 30 seconds.

The other gimmick is the UV sterilizer, which provides 99.9% sterilization and also operates on a 30-second cycle. Drop your phone into the slot, wash your hands as per the light ring timer, then both your hands and your device are clean.

The McDonald's sink in the Tweet above is a WOSH unit. The Japan Times reports that "some McDonald's in Japan" have installed them, though the depth of the partnership is not clear.

Currently, the systems are only available for sale in Japan, and international distribution will only happen when WOTA is able to drive their costs down. The prices are not listed, but the units are obviously expensive; as the company writes,

"The unit cost will initially remain high until the production process has been optimized. As a rapidly growing technology company, we want to be able to deliver the next product to the market at as low a cost as possible. That's why we've directed all our free cashflow towards R&D. By purchasing a WOTA product, you're helping us raise the funds we need to lower the unit cost of our products. With more sales, it will be easier for us to promote WOTA products in more markets as a sensible, money-saving alternative to water infrastructure – which will ultimately help society transition towards using small-scale, decentralized water reuse systems."