Salt water distillation

[garandman]

We have the situation of "water, water everywhere, but not a drop to drink." We're a couple hundred yards from the ocean. There is a river nearby but it's brackish and even if not would need to be purified.

Some lifeboats have "solar stills" that use sunlight and relatively cool ocean water to condense the water, but I've heard the quality of the water is pretty poor as some seawater always seems to get mixed in. Practical home solar still here but I don't think a solar still will cut it for a family in winter.

Big cruising sailboats have reverse osmosis watermakers but they are very expensive - $3,000 and up. I'm not on a boat so I can store 3-7 days worth of water pretty easily, but then I need to have a plan.

An efficient design would yield big benefits. Anyone else find plans or kit for a practical home desalination still? there are a bunch of videos on youtube but they're pretty basic. Seems I could do better than a piece of copper tuning attached to a tea pot...

 

[[cerberus]]

That is all a still is, a boiling pot, with a worm to condense the water vapor. Not much need to make it more complicated then that.

 

[garandman]

That is all a still is, a boiling pot, with a worm to condense the water vapor. Not much need to make it more complicated then that.

Correct - unless you need to be very efficient because you have limited fuel. How much fuel does your setup use?

Think I'll look into lab glassware and see if anyone has optimized the process with a glass condenser.

 

[06LemansC6]

No matter what you do it will take energy (fuel) to make sea water potable. Best bet would be able to capture the heat used for a still and use it to also heat the house, cook, etc. As you mentioned the RO units are expensive, use pumps that produce high pressure and use energy to operate. The RO units also require frequent and expensive maintenance as the membranes need to be replaced.

 

[MisterHappy]

First thing to do, is determine your dead-minimum potable water requirements; if you're on town sewer, then the brackish river water can be used for the toilet (it might jam up a septic system)

You might be able to drive a shallow well and get acceptable fresh water from it, as the "fresh" water tends to float above the "brackish" water.

Distillation is a very energy-expensive method of procuring water....that's why it's not used everywhere. Capturing the heat for re-use is a good plan....but not in summer. If you have a moonshiners' still - a pot with a worm, and a collection pot, you'll have a crapload of energy loss. It depends on how much you need and how badly.

Analyze your needs, and wants, then see what it will take. If you have a source of "not clean", but not brackish water, the energy needs to boil it to purity will be much, much less than what's needed to get the same volume all to vapor. Chemical treatment might be an option, too.

 

[hminsky]

Maybe you can get a used reverse osmosis machine from a boat?

 

[dnepro-mike]

there are semi-portable reverse osmosis systems that won't brake your bank, and don't require any power, just pressure of the water.

 

[garandman]

there are semi-portable reverse osmosis systems that won't brake your bank, and don't require any power, just pressure of the water.

I was excited to hear about that, but it turns out most need city water pressure. If I still have city water pressure it will be easier to just boil the water and let it cool.

Even the hand-pump MO systems are over $2,000. I can store one hell of a lot of water for $2,000.

 

[06LemansC6]

For the $$ and effort involved you may be better off investing in rainwater collection and purifying from there.

 

[garandman]

For the $$ and effort involved you may be better off investing in rainwater collection and purifying from there.

Sure looks that way.

What do people do with rain barrels in winter? The manufacturer says not to use them if there is risk of freezing.

 

[06LemansC6]

Sure looks that way.

What do people do with rain barrels in winter? The manufacturer says not to use them if there is risk of freezing.

You could bury them below the frost line and use a manual pump.

 

[Hiltonizer]

For the $$ and effort involved you may be better off investing in rainwater collection and purifying from there.

This.

You may even be able to get well put in, just a basic hand pump.

 

[garandman]

This.

You may even be able to get well put in, just a basic hand pump.

I live about 200 yards from the ocean, about 20-30 feet above sea level.

I got some plans for a solar still and got enough tubing to make an efficient heat exchanger, so along with stored water and rain barrels we got options.

I'm also going to map the nearest reservoirs. There are a number of them in Boston. I learned in passing that the capacity of the Quabbin Reservoir is 412 billion gallons. The Wachusett Reservoir is "only" 65 billion gallons, Chestnut Hill (held as an emergency supply) 500 million.

 

[Scarecrow]

I know there was one guy who lived for a while in a survival situation with the standard solar collection setup. dig a hole and line with plastic, leave a hill in the middle with a pot on it, cover with a tarp and put a rock over the pot so the condensation will drip in. Seawater won't cross contaminate, so that is not a concern; biggest issue is that it is a very slow system, so you'll only get the bare essential you need to survive, the rest of your daily needs come from food. Works well when you can clean dishes in the ocean, so you don't have to purify enough for cleaning as well.

I'm sure you could make several of them in an area to increase your stores, and use it to supplement rainwater.

 

[garandman]

The big difference between my house and my boat: we've got glass, lots of glass. Making a solar still with glass panels is pretty easy, just doesn't do much for you at night....

 

[greeniron]

Garandman....I mean no offense here but I cant follow your post. I try to read what you typed but I keep looking at the picture you have under your name. I am going from Salt Water Distillation to salt water....beach...girl on beach (focus)...hot girl on beach...hot girl on beach wearing tight green top with huge t!ts popping out (focus)....no water...dehydration....dying on beach with smile and thirsty....

 

[garandman]

Marisa Miller....

 

[ShadeWPI]

The big difference between my house and my boat: we've got glass, lots of glass. Making a solar still with glass panels is pretty easy, just doesn't do much for you at night....

Another luxery you have in a house that you don't have in a boat is space. The efficiency of solar stills is largely based on the exposed surface area of the sea water. Many require a large amount of heat because they are trying to generate a lot of evaporation in a small surface area. If you're building your own for in-house use, using a much larger area will greatly help. If you'd like to run an experiment, get a dark metal or black jelly roll pan and pour 1 qt of water into it, find a spot that receives full sunlight and lay out a thick towel. Now set the jelly roll pan with 1qt of water in it on the towel and check back about once per hour to see how the water level is. You might be surprised how fast the water evaporates using just ambient heat. Add some insulating glass and a good solar reflector and you might be able to get a reasonable water supply without needing a lot of waste heat to distill it.

 

[coastie]

How long are you planning on surviving in Dorchester? My MIL lives there and I just dont see it as a viable long term place to survive.

 

[Mattyweb]

How long are you planning on surviving in Dorchester? My MIL lives there and I just dont see it as a viable long term place to survive.

I was thinking the same thing. How much effort do you want to put into bugging in there vs GTFO. Pretty sure if water is interrupted there, you are going to have bigger issues.

 

[Timber]

Check out Kamen's Slingshot. Clean water distillation designed for 3rd world countries. Thing runs on a methane generator. You can literally burn cow chips to distill clean water from sewage. He just signed a deal with Coca Cola to get it out there. Very cool stuff.

 

[Boghog1]

Just ran across this one today, not sure how well it would work in NE but it looks simple to make. in the winter snow might be plentiful for fresh water

Eliodomestico Solar Still: Turns 5 Litres Of Sea Water Into Fresh Drinkable Water Per Day |

 

[patrickiv]

I've been thinking about making a small, portable desalination device(portable because I don't own any property). In the process, I came up with a few ideas to increase efficiency:
1. Instead of heating a tea kettle, just heat a small length of copper tubing that the untreated water flows into. This will start making steam faster than using a tea kettle.
2. Encase the tubing in a mini ceramic chiminea that contains a small fire and keeps the heat in. I have a regular chiminea in the back yard and it gets much hotter than an open fire of the same size.
3. If electricity is allowed, just use an electric tea kettle.
4. If running an old generator, put a tea kettle on the engine block or add an exhaust extension that wraps around the kettle.
5. Get an old big-screen TV and take out the fresnel lens. Focus sunlight on the copper tubing or tea kettle.