How-to: Remove bacteria from water using sunlight
By CG Lifestyles & People Editor Neal Patten
Happy Independence Day!
With today shaping up to be one of the hottest Fourth of July holidays in history, you shouldn’t need reminding about the importance of staying hydrated. Remember: sustainability goes beyond preserving our planet – sustainability of personal health is equally important. While having fun and enjoying juices, sodas and alcohol is a staple of today’s celebrations – nothing is more essential to protecting your mind and body than water.
H20 is blue gold – the Beverage Marketing Corporation reports that nine billion gallons of bottled water were consumed in 2011 alone. That’s just bottled – not home tap water or restaurant fountain water. There are various schools of thought on what is better for you – tap or bottled water. Companies selling bottled water make many claims about why their water is better than tap, citing everything from the pH level to neurotoxic dangers of fluoride (a national additive to municipal water systems meant to strengthen teeth.) While you should conduct your own research on the matter and not just believe what labels and your eco-conscious friends tell you, the fact of the matter is this: bottled water is not as safe as bottlers would have you believe and city water is not as dangerous as rumors have made it seem.
Neither tap nor bottled water is perfect – it really comes down to what you believe is worse for you. Are you more afraid of trace chemicals, trace metals, or trace bacteria? City waters are heavily treated with chlorine to remove bacteria and industrial pollutants, but the removal is merely down to acceptable Environmental Protection Agency standards known as Maximum Contaminant Levels. Furthermore, corroding pipe systems allow for the introduction of zinc, lead, copper and other metals into tap water. On the other hand, the Food and Drug Administration oversees bottled water but does not have the regulatory powers to enforce lab testing or violation reporting. That means the government is in complete control of tap water and knows exactly what consumers are drinking, even if it is not always 100% pure. Bottled water is left to manufacturers to self-regulate and the government is completely hands-off.
Full disclosure: for various reasons from the dangers of endocrine disruptors (Bisphenol A) in plastic, the fact that over 80% of plastics end up in landfills every year to the lack of water quality regulation and the irreparable destruction of watersheds for sourcing – I do not believe anyone should purchase or consume bottled water brands.
However, this is a how-to and not a soapbox.
I just wanted to make it clear for the purpose of this week’s Do-It-Yourself project that the concept of 100% “pure” or 100% “safe” water is a myth. You will not find it in municipal water, bottled water, or well water. However, there is a free and easy way to eliminate waterborne bacteria that does not require tablets or filters: good old sunshine! It may sound like an old wives’ tale but it’s true – in a matter of hours you can kill all of the germs in drinking water. All you need is an empty plastic bottle, a reflective surface, a sunny day and water.
Here is what to do:
1. Choose an appropriate plastic bottle.
There are seven classifications of plastic. The classification is typically found on the underside of the bottle, shown as a number surrounded by what looks like the recycling arrows. The symbol is similar but it is not an indicator of if the bottle is recyclable. Plastics 1, 3, 6 and 7 are not advisable for re-use. They are known to leach chemicals that disrupt hormones or cause cancers. Plastics 2, 4 and 5 are proven to be safer. For this project, a glass or steel bottle will not work, as they are too reflective. Mainstream beverage makers use plastic #1 (polyethylene terephthalate) for their bottles. There is conflicting evidence on the safeness of re-using plastic 1. If you are in a survival situation such as a camping expedition, you will be okay to re-use a PET bottle once or twice. However, some consumers are in the habit of re-using soda bottles over and over, which is definitely not safe. To purify your own water on a consistent basis, you will have to use unconventional clear bottles. Soap and syrup bottles are both made with plastic #5. Milk jugs are made with plastic #2. Try to keep the bottle under 3 liters, as the effectiveness of solar purification lessens with increased water depth. It MUST be a clear (or only slightly opaque) bottle – colored bottles are impenetrable (so remove any labels!). Be sure to thoroughly wash out whatever bottle you choose before proceeding. Don’t scrub too hard – scratches on the plastic will deflect the UV rays.
2. Fill the bottle up ¾ of the way with water.
It is important to leave air space. If you are using a new bottle of water, pour out ¼ (somewhere environmentally useful like a plant or your toilet tank!). If you are sourcing your water from the wilderness, seek out running water, not stagnant. Look for the deepest, clearest part of the source to fill your bottle. You can also stretch a bandana, sock or shirt over the bottle lid before filling to obstruct small solids. Cloudy water will take longer to penetrate therefore longer to purify. Thickly dirty water should be filtered before purification.
3. Shake the bottle.
Shaking the bottle up and down for 30 seconds will oxygenate the water. This is important.
4. Place outside.
Lay the bottle flat, not upright, on blacktop or a reflective surface such as a mirror, corrugated steel or aluminum foil. If you plan to purify in multiple bottles at once, lay them all in the same direction to maximize exposure.
On a 100% sunny day this will take 4 hours for decent purification and 6 hours for 99.999% (yes – 5 nines, it really works that well) purification. On a day where there is 50% or higher cloud cover, wait a full 24 to 48 hours before consumption. If water temperature exceeds 122 degrees, only an hour is needed for complete purification. Outside temperatures do not really matter, only the amount of UV exposure.
Just a sample of bacteria killed by this method: Vibrio cholerae (cholera), Escherichia coli (E. Coli), Salmonella and the parasite Giardia. This will not remove organic compounds from industrial waste or trace metals. However, it will remove all of the bacteria found in your well, tap or bottled water. So if you are wary of the Maximum Contaminant standards set forth by the EPA or distrust the self-regulation of bottlers, then this method will guarantee your water is free of unsafe bacteria, parasites and viruses.
The World Health Organization states that more than one billion people have unsafe drinking water sources. This results in the deaths of millions each year. That makes it even more inspiring that water can be rendered completely free of bacteria in 48 hours or less by simply re-using existing plastic bottles and the power of our sun’s Ultraviolet rays. This purification method is officially known as SODIS (solar disinfection) and is recommended by UNICEF and Red Cross. For further reading, visit this website funded by the Swiss Federal Institute of Aquatic Science and Technology.
So the next time you find yourself reaching for a case of bottled water at your local grocer or cringing at the notion of drinking tap water – take a few minutes to fill up some bottles with clean (free!) water, go outside and utilize the amazing power of sunlight!