It is a joke, right? If you can purify urine with something like that, all you'd need is to get users "contributing" to the system.

Not a joke in the slightest. It is a distiller, so clean water boils off and is collected, separated from any contaminants.

Yeah, I know. But most of the problems that poorer nations face are not related with complete lack of water, but with the lack of drinkable water. The droughts you mentioned are oftentimes the same.

I really don't think there is a lack of water. Just lack of drinkable water. Unless you are in the middle of Sahara, you should be able to find all kinds of water sources.

There's also lack of energy... do all the distillers come with free solar panels? Otherwise you need to have fuel.

That's why the article refers to the Stirling engines as a potentially partner - you chuck your cow dung or whatever into the Stirling to generate the heat needed to distill the water

Not only that, you get electricity out of the engine as well. The waste heat from the electric generator is used to power the water purifier.

The numbers in the article suggest the stirling engine needs 1kW of energy input. There is no need to use expensive photovoltaic panels. 1kW is about 1 square meter of mirrors in a solar concentrator on a sunny day at many latitudes. Solar concentrators and stirling engines pair nicely, though there may be issues at that small scale. Nothing more mirrors won't fix though.