Purifying Water Using Passive Solar Water Distillation

Passive solar water distillation is an inexpensive, low-tech alternative for pure drinking water without bottles, including types of distillers, cost comparisons, going automatic or electric.


| August/September 2002



Pure drinking water can be produced with energy from the sun, in a process known as passive solar water distillation.

Pure drinking water can be produced with energy from the sun, in a process known as passive solar water distillation.


PHOTO: EYEWIRE

Learn how to use passive solar water distillation to purify your drinking water.

Americans worried about the purity of their well or tap water often end up spending a small fortune on bottled water just to be safe. But bottles aren't the only solution. For those who want to produce their own pure drinking water, passive-solar distillation is an inexpensive, low-tech option.

Passive Solar Water Distillation Solutions

Distilling and reverse-osmosis filtering are the two best methods for purifying water. Both approaches remove more contaminants than activated carbon filters do. The U.S. Environmental Protection Agency says only reverse-osmosis systems and distillers may be called water "purifiers." All other systems are water "treatment" devices, in spite of the performance claims many manufacturers make. But reverse-osmosis filtration wastes water: For every gallon of purified drinking water produced, the process consumes 2 to 4 gallons of water. In contrast, solar distillation wastes no water and is powered by the sun. instead of removing specific contaminants, as filtration systems are designed to do, solar distillation purifies water by removing only one thing: water.

Distillation takes advantage of the principle that chemicals vaporize at different temperatures. Most potential chemical contaminants in drinking water have vaporization points higher than water. When untreated water is heated in a solar distiller, pure water vaporizes first, leaving contaminants behind.

A simple solar distiller removes salts, heavy metals and bacteria, as well as arsenic and many other contaminants. According to a paper by Horace McCracken, a leader in solar distiller design, laboratory tests show distillers can remove trichloroethylene (a dry-cleaning chemical) and nitrates. Both are common pollutants and suspected carcinogens. A simple solar distiller paired with a carbon finish filter which removes any residual chlorine byproducts, will give you the cleanest drinking water for the least expense.

Simple Solar Distillers

Solar distillers work by mimicking the natural water cycle: The sun provides energy to warm the water, the water evaporates (forms clouds) and condenses (makes rain) when it meets a cooler surface. Unlike electric distillation, boiling is not required for solar distillation. Some people believe water from a solar distiller is purer than boiled water. Florida Solar Energy Center principle research scientist W.R. McCluney, Ph.D., says vigorous boiling "can force unwanted residue into the distillate (distilled water), defeating purification."

ddsoffice
8/24/2014 5:54:48 PM

Since a full grown adult's body is anywhere from 50% to 65% Water (for youth it's much greater-Infants is around 75%-80%!) all water consumed means that YOU become the filter of whatever is in that water therefore, no matter the source, ALL of your water should come from a filtered source or at least one that receives scheduled assays where that water meets or exceeds EPA standards. Why do I mention this? Recently I looked at a piece of residential rural property on 4 acres that has its only water source as a well and the wife of the owner has a slight tremor in her hands with some twitching around her eyes. I didn't say anything but when me and my husband got back home he told me what the husband of the couple selling the house said about arsenic in the well and other contaminants and that when he bought the property 10 years ago they knew nothing about water contaminants until 7 years later when their Dr. explained the most likely cause of the development of his wife's tremors and twitching was due to the arsenic in the wells of Silver Springs, Nevada (an assay revealed how bad theirs was; a very scary thing!) Since all private wells are EXEMPT from the US Water Quality Act sellers of such properties do not have to say anything about it and many in rural America who are ignorant of chemistry and the facts of contaminants use unfiltered (for arsenic and the naturally occurring radon, radium, uranium, polonium etc.) you need reverse osmosis filters at minimum with assays at least once per year to make sure. If we decide to move to such a place we will make sure to have a whole house reverse osmosis filter and in addition, a water distiller in the kitchen. The last thing we would want is for my husband's kidneys to have any more damage than they have from Agent Orange in Vietnam or nasty things like cancers of the stomach or any other body part! Perhaps Mother Earth News might want to have an article that includes scientists sharing resources to educate the public along with a list of links to spec. sheets for various reverse osmosis and distiller systems. Thanks!


diwakar
9/9/2013 8:16:26 AM

In southern parts of India we have bright sunshine for 9 months and the ambient temperature does not fall below 26 degrees celcius. In Bangalore City, Karnataka, India, solar water heaters are very popular and many houses have roof top solar water heaters. This device is a finned copper tube heat exchanger working on the principle of conduction convection and radiation of heat from the sun. My question to the learned people is, is it possible to connect the solar water heater to a water distiller ( http://kids.britannica.com/) and harvest the condesnate for better yield.


kelvin
6/3/2007 1:31:07 PM

Hi, well I don't know is the solar distiller is 100% pure water, because for that the water must boil (go over 212F). I would try better the Waterwise Water Distiller...






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