purify salt water

[xrayoneone]

Also if it is a scenario where you do not have the means to boil the salt water you can set up a solar still. With the salt water in a small puddle place a cup in the center of the puddle that is taller than the puddle is deep. Place a plastic sheet over the puddle, anchor and seal securely and then place a small rock or other weight in the center of the plastic. The sun/heat will cause the salt water to evaporate, condensation will form on the sheet then run to the center and collect in the cup.

It takes a long time. I've tried it for shits and grins and it worked okay but you would probably die of thirst with the out put of this thing.

[Allen]

http://www.landfallnavigation.com/me...mpaign=froogle

Have not used it, but have been told that something similar is still issued by the Navy.
Allen

[whiskey lake]

Generally speaking (exceptions to every rule) it is almost impossible to desalinate enough water manually to last long term. The energy expended in boiling and collecting the steam is counter productive. You need a pretty complex operation to gather enough water.

[762xIan]

Reverse osmosis would work, but salt water is really hard on the membranes. RO's also require a pump (electricity availability) to provide the high water pressure for the RO to work.

Easiest in the field way to provide safe water is distilling. If I had enough pots, tubing and plumbing fittings, I am sure I could cobble something together. Boiling will kill anything in the water, all solids and salts stay behind in the boiler and the steam leaves it through tubing or piping.

An air cooled coil of tubing will condense your pure water into a container.

The biggest problem is a safe boiler, or a way to remove it from the heat if the pressure gets too high. Boiling pressure vessels will explode if you don't have things right. As your pot boils off you need a way to add more water to it and also get rid of the concentrated "brine". Pretty doable, but it won't be a very portable set up.

The other problem with a distilling operation is smoke/odor from your fire attracting attention. You would also need close proximity to the water source and a steady fuel supply.

[Koshinn]

http://en.wikipedia.org/wiki/Solar_still

[762xIan]

The one thing I have against solar stills is the low volume, plus the OP says he is in the Chesapeake Bay area, cloudy days and winter time will affect production or make them useless.

I made a few solar stills, one using a hole in the ground and a rock on plastic, made a half a cup of water in a day. With the scouts, we made one using a kiddie pool, and distilled off a quart in about 4 hours of sunshine.

Also is there any kind of test to determine how salty the water is.

Short of buying expensive lab equipment to determine exactly which salts are present? The easiest is one of those pocket TDS meters, a decent one is usually around $100. It won't tell you specifically salt content, but will give you ALL dissolved solids in the water. Usually anything below 500 is safe to drink solids wise, but will require chlorination.

One of those would give you a good relative idea of how "hard" the water is. It could mean the difference between adding some chlorine to low TDS water to kill any bugs, to having a very high reading and looking at having to distill it to make it drinkable.

If you specifically want to see salt content, I know some pet stores have hydrometers and other test equipment for salt water aquariums. That stuff is pretty cheap compared to lab quality stuff.

Here is a link to the EPA on drinking water standards and the maximums of contaminants that can be in water, pretty good definitions at the bottom also (scroll down): http://water.epa.gov/drink/contaminants/index.cfm

[Koshinn]

The one thing I have against solar stills is the low volume, plus the OP says he is in the Chesapeake Bay area, cloudy days and winter time will affect production or make them useless.

I made a few solar stills, one using a hole in the ground and a rock on plastic, made a half a cup of water in a day. With the scouts, we made one using a kiddie pool, and distilled off a quart in about 4 hours of sunshine.

http://en.m.wikipedia.org/wiki/Water_Pyramid

Scale it up. 1000l per day!

[calebgriffin31]

Another thing with the solar stills. They do have their place. Although one still will not produce the amount of water necessary, multiple stills can. If you are digging holes for stills, you are obviously staying in that area for an extended period of time and can dig more than one still. Additionally, if some sort of tubing is placed in the collection device, the water can be removed from the still without having to disassemble the still.

[trinydex]

if you have time and opportunity to make a solar still then why not just set up a system for distillation? you could boil the water and pipe it into a condenser of some sort and make distilled water.

https://en.wikipedia.org/wiki/Distillation

[THCDDM4]

Distillation is your best bet. As others have stated. Solar or otherwise.

You can also use DE to filter salt out as well. I cannot locate the info on this currently, but will try to locate the info and post it at a later date.

Basic diatomacious earth filters can be found in homebrew supply shops and online that would work for this- using the proper DE.

Basically you can use the ground/soil to filter out the salt and collect the ground (Desalinated) water by digging a trench or setting up a mini well with hand pump.

Once lockheed brings "Perforene" to the market, RO filtering of salt water will be much more realistic and effective without such high amounts of pressure needed to push the water through the membrane- making RO systems small/portable enough to be used in survival situations.

Have no idea when it will be brought to market though...