io9.com has an article on Nanotech sachets that use inexpensive materials (nanofibres and activated carbon particles) in a ‘teabag’ form, to use with individual-sized water bottles. Although it seems like it would be very affordable, I’m not convinced it’s such a good thing, as these disposable teabags only will purify one litre of water, but I can see it being used in an emergency. Then again, I’d rather have a sustainable ceramic filter, or the very compact activated-chlorine-dioxide (like in Pristine water purification) for point-of-use filtration. The former is heavy and requires a (small) effort, but is great for canoeing, since you can filter nice clean water on the go. The second is nice and light and small, but is not as sustainable, and requires waiting time. The focus is on relief efforts and helping under-developed countries, but I can’t help but think a proper, larger-scale purification method would be better for the long term, and for the smaller scale solution, something like the Lifesaver bottle might be more appropriate.