- https://www.survivorfilter.com/products/pro-series-virus-met...
Products like this are tested against water quality standards and can probably can achieve a better performance/price ratio than what you can build yourself unless you're planning to put significant time and effort into this project.
There are universities working on this problem as well who might already have some projects in progress such as: https://news.mit.edu/2020/passive-solar-powered-water-desali...
If you're planning to build your own system for your own amusement or education, then you should first decide how pure do you want the output fresh water to be, and what is your resource (time and money) as well as energy budget?
1. Reverse osmosis seems like the most pragmatic solution: https://en.wikipedia.org/wiki/Reverse_osmosis#Fresh_water_ap...
You can buy inexpensive membranes, water pumps, and solar panels from places like AliExpress but might need to perform modifications to generate the required pressure:
- Reverse Osmosis Membrane: https://www.aliexpress.com/item/32669709750.html - Solar-powered fountain: https://www.aliexpress.com/item/4001095938363.html
2. Solar still: use mirrors to focus sunlight and evaporate water. Easy to build but only practical in climates that receive lots of sunlight, only works during daytime.
- https://en.wikipedia.org/wiki/Solar_still
3. Electrolysis: probably not practical for filtering lots of water on a large scale because it's slow and energy-intensive, but can result in the purest water. Buy a solar panel, put positive anodes and negative cathode into the water to break it down into hydrogen and oxygen, and then wait for a long time.
- https://en.wikipedia.org/wiki/Electrolysis_of_water - https://en.wikipedia.org/wiki/Water_splitting
If you're planning to drink the water for extended periods of time, it might also be a good idea to remineralize the water:
- https://thewatergeeks.com/how-to-remineralize-ro-water/
Also be aware that if you store the water in a plastic barrel, certain phthalates might leach out which could be carcinogenic or interfere with your hormone system. It might be a better idea to use a stainless steel or glass container.
- https://www.vox.com/science-and-health/2018/9/11/17614540/pl...
What I'd be looking for in a collaborator is people who are able to spread the word about why this is a good idea or perhaps even advance the idea by selling kits at cost to help get them out in the world for cheaper (assuming bulk discounts). I'd also be looking for a better biologist than I (or whatever kind of scientist I'd need for this part) to help me make sure that the filtration is adequate to ensure safety.
I want to learn more about the required filtering. I have a barrel and I've bought a lot of fancy cartridge filters from McMaster in the past (I do chemical engineering and am weaker on biology), so I feel like there must be a way for me to do this.
The reason I worry about this is because in a power outage the city water supply can go dead. Or an earthquake if you live in a region prone to them. Or a flood could contaminate the water supply. I think that in such a scenario you should have 10 gallons of water per person tucked away so that you can keep yourself healthy and also help your neighbors.
This is a simple project I can try to document and do in a way that is definitely safe (the last thing I want to do is give unsafe advice). It is a project that would likely cost someone a hundred dollars or a bit more, but increasing household resiliency seems increasingly important.
I remember growing up that we always had emergency supplies because it's important in a serious emergency to not depend on emergency responders (with limited time and lots of problems to handle) for basic stuff that you should be able to handle yourself with fairly simple preparation.