Although not very practical for producing large amounts of water or quickly, if portability and being able to operate without power are primary concerns, forward osmosis like HTI's product seems like a good choice for what you're describing.

Reverse Osmosis pumps will remove most of nitrates, phosphates and heavy metals from water. I would assume this will clog the filters of any hand held pump pretty quickly, but how quickly, I have no idea (and having no access to a lab I can't really tell for sure how effective they are).

The problems with ROPs are price, tiny volume of purified water (the manual life raft model produces about 1-2 litres per hour of manual pumping, the electricity run models are pretty decent but obviously, require a power source) and need for special replacement filters. On the plus side, they also desalinate sea water and remove most of the taste from any water.

For situations where you don't have access to such a pump. I would probably let water stand in a bucket until sediment falls to the bottom, scooping the top 2/3-3/4 and repeating the process two or three times. After that, add any normal water purifications and hope for the best.

-jh

Hope it rains and get your tarps and containers out.

If you're talking about your home area, contact your local Water Board and ask them what kinds of contaminants are in the local water (they know). Then ask what would be the best, least complicated way to deal with them in a major disaster situation.

Use the info now that is already available. Waiting until a problem erupts and then guessing on how to deal with it would seem to be the height of poor planning.

Sue

A bit further into the water purification thread linked:



Apparently it is not a time but rather a volume consideration. But don't take my word for it, I am by no means an expert. Blast on the other hand ...

Natural water sources were never really safe. What bears do in the woods, beaver fever (also known as giardia), naturally occurring alkali and arsenic, there are even some plants that can poison water in some rare situations. Point being that you can't assume the water is safe to start with.

Then you add humanity, leaking septic tanks, people squatting in the woods. Things get worse if those people are maintaining a golf course, grassy areas, growing crops with lavish applications of fungicides, herbicides, insecticides, fertilizers. But on top of this you can stack the abominable behaviors of country gear-heads dumping their used motor oil, agricultural and industrial dumping, general human carelessness and callousness.

But even that may be just the start. Consider the standing water in Haiti, or Japan after the tsunami. Mama was very careful with how and where she used that insecticide. She kept is sealed in its bottle well away from hard. Them the wave came along and ground her lovely and orderly home, and that bottle of insecticide, to splinters. The answer to the question; what is in the water is like the old James Dean line. When asked what he was rebelling against he answered back 'What you got?'. Pretty much every chemical, fuel, virtually anything that could get into the water is in there in some amount.

First way to get around this is to try to find cleaner water. Any rainfall, outside that falling through smoke from fires, or vapors from the nuke plant, should be collected. Outside that careful consideration of what is in the area is helpful.

After that some mix of skimming, settling and crude filtering would be a good start. After that carbon filters would be one way to go.

The other way is what Richlacal suggests.



Distillation would work well I think. I'm thinking of something like a Sierra stove. A stove that will allow you to convert the huge mounds of scrap wood into distilled water, hot food, warmth.

Forward osmosis systems could potentially remove chemical contaminants. See http://www.247water.org/. They advertise it as working on contaminated water.

Basically, they have a sugar/salt syrup on one side of a membrane. Dirty water goes on the other side. Osmotic pressure pushes H2O from the dirty side to the clean side.

Never used it myself but thought it might be worth having a couple of the emergency use versions in a kit.

Fuel and/or time intensive, not very mobile, and a number of contaminates evaporate as well and would condense in the system. Petrochems mostly, but IIRC there are some other ag chems that won't mind. You'll get out heavy metals and salts, so if you got the time, fuel, material and don't mind relatively low output, sure.

I believe the Seapack and Hydropack kits, the ones that use a syrup to promote osmosis, don't yield pure drinking water, but rather a sweetened drink, similar to sports drink. I recall reading something that sweetened drinks, including sports drink, aren't ideal for rehydration. Then again, gotta be better than nothing.

Maybe once things settle down in Japan there will be some new studies on the effectiveness of various filtering methods and devices to deal with these types of situations. Hopefully Consumer Reports or a similar objective organization will perform a scientific rather than empirical study.

Forward osmosis is an interesting concept, but I was not impressed by the amount of water they provided - something like half a liter per capsule, and that over a very long period. In any situation where you are doing even moderate work, that amount of water is minuscule. For most applications, it would be much simpler merely to pack the water in the first place.

I have had good experience with sports drinks for rehydration, although I usually dilute Gatorade about fifty-fifty with water. It is better that way when working hard.

A relevant excerpt from Zen Backpacking...............


http://zenbackpacking.net/WaterFilterPurifierTreatment.htm

The US military uses Chlor-Floc water purification tablets which uses aluminum sulfate as a flocculating agent.

Flocculating agents allow for removal of suspended solids in water by promoting rapid clomping and sedimentation of fine particles suspended in water. This sediment is then easily removed by straining the water through a cloth or by siphoning or pouring off just the clear water. This isn't a "filter" treatment in itself but allows for the removal many suspended solids to improve clarity and taste of water as well as decreasing the amount of treatment (chemical/filtration/heat/radiation/etc) needed for your water.

Flocculating and coagulation can remove 60–98% of microorganisms, heavy metals, and some chemicals and minerals from water.