The invention helping Cambodian villagers produce clean drinking water

August 1, 2023 10:11 PM

The invention helping Cambodian villagers produce clean drinking water for free. A small sticker that uses UV light to indicate when contaminated water is safe for drinking is revolutionising life for villagers in South-East Asia.
posted by chariot pulled by cassowaries (8 comments total)

This is such a great idea, just enough technology to do the job (with a ton of thinking, asking and observation to get the tech side as minimal as possible).

A friend of mine did this kind of work, usually brought in after a big-funded tech-heavy project had failed (always due to a lack of thinking, asking and observation), and they'd come up with something simple that worked.
posted by unearthed at 11:07 PM on August 1, 2023 [5 favorites]

It seems like this ought to go inside the bottle somehow. Anti-UV treatment in plastic is a thing.
posted by Kid Charlemagne at 5:34 AM on August 2, 2023 [1 favorite]

This is a great idea. I treated my drinking water this way when I was in the Peace Corps. To be conservative I'd leave the bottles on the roof for a full day of tropical sun, though I knew it would be safe faster than that. Other volunteers were mostly filtering or boiling their water, but it was so much less work to just put bottles on the roof in the morning and collect them late in the day.

For cloudy days, I had bleach as a backup, or could boil, but with a bit of planning ahead based on weather that usually wasn't needed. Having a sticker to confirm that it was "done" would have been great.
posted by Dip Flash at 7:00 AM on August 2, 2023 [2 favorites]

A little bit of good news on a cloudy day today.
posted by BlueHorse at 9:25 AM on August 2, 2023

I couldn’t tell from the article; does the sticker “reset” after being out of the sun for a few hours so it can be re-used again and again?
posted by blueberry at 2:03 PM on August 2, 2023 [1 favorite]

Even the safe sticker website doesn't say though some of the funding appeal phrasing makes me think if not single use they have a fairly low lifespan. I wonder if they are trying to avoid some sort of misplaced hand wringing about waste.

Also the stickers work with glass bottles which I'd thought blocks UV light but TIL regular glass only blocks UVB and is transparent to UVA. Which explains the sun burns I've gotten while driving (it's been somewhat weird to have to put sunscreen on while in a car).
posted by Mitheral at 8:17 PM on August 2, 2023

I assume the smart way to use the stickers would be to put one on a group of bottles and then you’d know they were all safe when it turned color. It wouldn’t function as a sign per-bottle, but you already have to depend on the goodwill of the “producer,” since they could just refill a already-consumed bottle.

I’m having a hard time imagining if clean drinking water is too expensive that these stickers wouldn’t be themselves a significant cost. Anyway, sounds like a good idea.
posted by Gilgamesh's Chauffeur at 9:41 AM on August 3, 2023

Clean drinking water is a hard problem and pretty expensive on an individual basis if you government doesn't enable it. (Hell as Flint and Memphis show it's a hard problem even if your government does nominally enable it). The sticker site says that the program is affordable for the users even when they make $2 a day and yes they point out that only one sticker per group of bottles is required.

That means, if a community works together, thousands of litres of water could be verified to be drinkable and safe via SODIS by just ONE SAFE Sticker. ... more than a thousand SAFE Stickers can be packed in a container the size of a deck of cards. This makes them easily transportable, so they can reach very remote communities and areas with a higher level of ease than any other form of water disinfection.

One of there donation levels is $50 for a years worth of stickers for a family. That is 14 cents a day assuming one sticker everyday for a family and then only if the package doesn't include any bottles.posted by Mitheral at 11:24 AM on August 3, 2023 [1 favorite]