Heh, not a bad idea Is there no end to the usefulness of a sheet of clear plastic and piece of aluminum foil?

Re, flocculants: I ran into a study on various flocculants looking at how well they precipitated heavy metals (specifically, the study was about arsenic -- I could probably dig it back up). The candidates ranged from 40-90% of arsenic removed -- not perfect, but certainly better than nothing. Boiling doesn't remove any heavy metals, and filters (even activated carbon) usually don't remove much. Flocculants do remove a significant percentage of microbes, although you obviously don't get the 99.99...% that you get with a good filter. I seem to recall the numbers that I've seen being something like 80-90%.

Re, ph: I ran into another study on clostridium (heh, it was all of these studies that got me curious) -- the genus that includes the sources of botulism, gangrene, colitis, tetanus, and others -- which mentioned that they're very sensitive to low pH (I think it was a pH of 5.0 that was lethal to them), and lowering the pH is a good way to waterborne clostridium species. I've ran into pH treatments for other species as well, some high, some low -- don't remember which species were which, though. Certainly, of course, some diseases are hardier than others. I'd imagine that most cystic species, such as giardia, would probably be resistant to pH changes.

Thanks for all the feedback Don't plan on actually using any of these techniques any time soon, but just trying to flesh them out in case I ever do.

Here are some others, mentioned before in other threads.

Sodis- solar water treatment using the sun and a large pop bottle.
effective on bacteria and virus.

Sari cloth filter combined with settling,
good for cholera.

biotic sand filters,
after a couple of weeks, biotic organisms grow that will
eat even metals as well as bacteria and virus. No need for charcoal. Locally they took care of a large diesel spill
by piling up the dirt and inoculating the soil with oil
eating bacteria.

Neat ones -- I'll definitely have to remember those Plastic trash can sometimes be found in the most remote places; other fine-weave cloth (for example, nylon or spandex) could probably fill in for Sari; and the sand filter sounds like it would complement the artesian concept nicely (it'd just require a larger, slower moving seep to give bacteria time to clean it; you'd probably have to mulch the top with dead grass or gravel to lower evaporation).

Yes, but only if you confuse them. The plastic cup might get tricky, and you'd have to be very skinny to stay dry under aluminum foil.

Here is a link to a bunch of water treatment files for rural
and developing countries.

http://www.lifewater.org/resources/water_treatment.html#WT

Interesting that in this file:
http://www.lifewater.org/resources/rws3/rws3m.pdf

They claim that simply "storing" water in containers for 2 days or more will reduce the level of bacteria (up to 90% for two weeks). They do say that to be sure that it is safe the water would need further treatment.

While no help in a short-term situation and only somewhat better than nothing, this info might shed some light on our concerns about long-term storage of water. Perhaps time IS on our side.

Has anyone heard of this before?

No, but it might help explain why more sailors didn't die from tainted water (as opposed to scurvey, etc.) in the age of sail. Unpurified water dumped in an oak cask sometimes months before they drank it - ugh. I always assumed that it was natural resistance, but who knows?

Very interesting topic. More relevant to long-term situations, but definitely worth discussing.

I've heard that certain formulations of concrete are being used to create a slightly porous matrix that will effectively filter harmful organisms out of water. This was in the context of third-world development. It seems more likely that this would work better for larger organisms -- water-borne parasites, amoebas, protozoans, etc. that cause a lot of carnage in the developing world.

I don't have a link (yet) but will look around.

Interesting. Sort of like the Katadyn ceramic filters? I have one of those and just love it. Doesn't help with heavy metals or organic contaminants like pesticides, so you don't want to use it on agricultural or industrial runoff, but it's great for biologicals. When it clogs with bacteria, you just pull out the abrasive pad, rub off the outermost coating of ceramic, and it's good to go again; you can repeat hundreds of times on a single filter.

My filter is one of those siphon ones, which is nice and convenient. I ordered a few carbon filters last week and I'm going to try chaining one after the ceramic filter to take out organics; if it doesn't have enough pressure, I can extend the tubing to allow for a greater height difference in the siphon. Combined with flocculating the source water before the ceramic if it's particularly contaminated, it should be a killer system, able to take care of almost anything but saltwater. Even the volcanic runoff water that I encountered when hiking in Japan could have been made safe and tasty by including that last step**.

Of course, it's not useful in a "I find myself stranded unexpectedly!" situation.

** Instead of using premade tablets, I have the individual components used in modern flocculant purification tablets. That way I don't have the added chlorine compounds (which I don't need and don't want because of the filter) and can adjust the pH (more aluminum sulfate to lower, more sodium bicarbonate to raise) as needed. Much cheaper, too.