You can thank me later, but know that I just watched over three butt-numbing hours of videos about building your own solar water distiller to find only this ONE (two part) video that seemed sufficiently informative. There may be some better ones out there, but I didn’t find them. They each had a small piece of the project, but most didn’t really tell enough of the story. Of course, if you’ve seen better than these, please mention them in the comments section below this article, with enough information about the video we can actually find it.
You may be considering an expensive home filtration system, but if you have a large enough solar water distiller you may not need the filtration system. With a device that fits easily in a sunny corner of your backyard, you can distill up to gallons of water a day – with no expensive filter replacements – ever.
Please note this article is not necessarily about “emergency” water distillation, although, if you had the materials on hand this project would be great for that. It’s really about building something this weekend that can be used effectively now and in an emergency.
First, watch these videos from YouTube’s CrypticCricket, then come back here for the best practices (found below videos).
According to safemarkets.org, vinyl releases some of the most toxic chemicals on the planet over its lifecycle. So, even “virgin” vinyl is not really food-safe. Plastic with a recycle imprint number of 5 is polypropylene (PP) and is really the only plastic that is considered food safe. Unfortunately, you won’t find many building materials made of polypropylene. HDPE and LDPE (high density and low density polyethylene) are considered “low hazard” plastics when it comes to food and human contact. They are ok to use for food if you consider estrogenic chemicals in your food ok. These chemicals can cause severe health problems, even at low doses, for juveniles and babies. Note that ALL plastic items leach detectable amounts of toxic chemicals once exposed to boiling, microwaving, or ultraviolet rays (the latter of which is contained in sunshine).
The point here is – is you are concerned enough to distill your drinking water, you should be concerned enough to use non-toxic materials when making your distiller.
Best practices for building your own solar water distiller (found while watching hours of bad and so-so videos) are below:
The box should be as air tight as you can get it. The more air you let in, the slower the evaporation process and hence, the slower the condensation process – meaning less drinkable water produced. Large air leaks will equal NO condensation.
The heat inside the still can easily reach temperatures of 200 degrees Fahrenheit. Choose your materials using that temperature as your minimum guideline. Use UV resistant silicone sealant around the glass.
Water depth should be around 2 inches. If the depth of the water depth is more, it takes too long for the water to get warm enough to start the evaporation process. (Although this depth limitation could possibly be overcome with the addition of a Fresnel lens on top of the glass surface.)
Incline of the glass should be around 5-10 degrees. This amount of incline allows the condensation to drip down the glass efficiently. Less incline could allow the water to fall back into the water tray. (The incline of the glass in a distiller has little to do with solar absorption or angle to the sun. The sun passes directly through the glass; therefore it has a negligible effect on the heating of the water – so the 35 degree glass incline that some people are talking about has to do with solar collectors – not solar distillers.) The job of the glass is to trap the heat and provide a slick surface for the condensation to run down. Try not to use plastic for the top of the distiller. Plastic in the sun is just putting toxins back into your water and can sag. It will also haze over and let in far less sunshine in just a few months in any long-term direct sunlight.
Don’t recess the glass too low in your collector as a breeze across the surface makes for better condensation. The main contributor to efficiency for a solar water distiller is the temperature difference between the top surface of the water and the bottom surface of the glass. The greater difference between the temperatures of the two surfaces, the more condensation. Cooling the glass from the top can improve efficiency 5% to 25%.
Thin glass is better than thick glass, but tempered glass is way better than non-tempered glass. You’ll want something that can stand up to possible hail and, if your neighborhood is anything like ours, small furry animals romping up and down on the glass trying to figure out why they are not swimming already.
Clean the glass on the inside surface very well – then clean it again. When you think it is perfect, clean it again. Then, install the glass on the distiller as soon as possible to keep the dust from the surface you just cleaned.
To read more about the awesome design below, go to techedmagazine.
That’s it. Good luck. Please send me photos if you attempt one of the distillers in the drawing above. I also want to know how you built it and how it performs!