A Many people may choose this route, however I think people can get a concept of the process and design one that fits their needs at a fraction of the cost. Instead of looking at a single plan, people should consider their resources, and needs in producing a distiller that fits them. Distillers don't have to be powered by solar or electric: You can find stove top or fire powered distillers. Building your own can ensure that you use the safest materials for the distilled water to pass through. Many distillers use a stainless steel coil for condensing the water vapor. Some people are concerned about nickel and other bad metals getting in the water from the coil.
Here's a video on a rudimentary distiller:
Solar Water Distiller
Aluminum is toxic, but in this case any aluminum getting in the water will not end up in the distilled water. The plastic wrap however will contaminate the water, and would best be replaced with glass.
We designed a still which is easy to replicate, using standard building materials, of which 95% are available "off the shelf". The exterior materials were chosen for their ability to withstand our desert climate with minimal maintenance. The still produces an average of 3 gallons per day in the summer months. Winter production is expected to be 1/2 that amount. The Solar Still can utilize a standard size patio glass replacement, 34"X76". The material costs per still are approximately $150.
Brackish water is carefully placed inside Solar Still via an inlet near the base of the Still. As sunlight warms the black silicone bottom and heat is transferred to the water, the top of the water evaporates on to the inside of the glass cover, which is tilted toward the fresh water drain. approximately 8 square feet (of glass cover) will distill around 1 gallon of water per day, over five hours of full sunlight.
The most important elements of the design are the sealing of the base with black, high temperature silicone rubber; (spread it on with a Bondo squeegee) and creating a good seal between the glass cover and the bottom of the box.
-Though adding salt raises the boiling point temperature of water, it also increases the evaporation rate. Salt should only need to be added after each cleaning or flushing as the salt won't evaporate. Electric and commercially available distillers often need cleaning with harsh hydrochloric acid. In this case, the distillers are overfilled and flushed. Using the constant feed mechanism should reduced buildup on the bottom (where it's important for the sun to hit).
Here's a diagram of an array from the page quoted above: (more diagrams at that page)
Keep in mind that any sealant used on the glass has the potential to contaminate the water it produces, however the water should be run through an additional activated charcoal filter during the process (asap) to keep it from absorbing C02, and to filter out odors and other contaminants that make it through. The water being almost pure is going to pick up contaminants fast, so glass or another inert media is recommended from point of condensation and beyond. A continual feed setup (could be a bucket using the same principle as an automatic watering dish) would be convenient. The activated charcoal should be replaced approximately every 3 months.
Commercially available Activated Charcoal is produced in an oxygen free environment at a temperature of 600C. When you make your own it won't be as potent, so 3-4x as much as normal should be used. Use untreated, nontoxic woods or coconut shells. Char the wood at high temperature and break into ideal size pieces (surface area is key).
Ingesting Activated Charcoal is commonly prescribed for many cases of poisoning. There aren't many cases of poison ingestion that Activated Charcoal wouldn't help greatly with like caustic substances like lye, as well as salts like sodium chloride, potassium nitrate, iodine, fluoride, bromide, and mercuric chloride. which are aren't absorbed as well by the charcoal. Having Activated Charcoal on hand is convenient for those occasional accidental food poisoning incidents. Keep in mind that Activated Charcoal will absorb painkillers and other medications.
