Is rainwater safe to drink? Using ultraviolet, UV light, can be used to design your very own rain water harvesting system that disinfection drinking water for your home or business.
The gathering of rain water for human needs is as old as civilization itself. With the current trend towards sustainability, you may be interested in the ways that rain water might be “harvested” as an alternative to relying solely on municipal resources. For the homeowner, rainwater harvesting can range from simply collecting water in a barrel for taking care of plants to a full-fledged independent water supply for washing and even drinking. But is water from the heavens safe to drink?
In general terms, rainwater is distilled by nature in the evaporation cycle and so it comes down free of most contaminants and additives like chlorine. But as it travels through the air and comes in contact with surfaces such as roof tops and gutters it will pick debris and biological contaminants. In most cases these are minimal and can easily be managed. For example, you can use a first-flush diverter that catches debris from the roof in a trap before the clearer water flows into your barrel.
That’s all well and good for garden-use or washing cars, but protecting your family from harmful microorganisms requires proper disinfection of the rainwater. Long-used by well-water owners, an ultraviolet (UV) water disinfection system is a chemical-free way to ensure that your water is safe from biological contaminants.
The water is disinfected by light of a specific wavelength as it passes through a stainless steel chamber. Nothing is added to the water, but any microorganisms present will be rendered harmless. Rainwater is naturally soft and so will not require a softener, although some “polishing,” or added filtering, may be desirable for taste and ultimate particle removal. In fact, the newer, high-quality UV systems often come equipped with both a sediment and carbon filter for just that purpose, which makes installation all the easier.
Maintenance is also easy – just an annual lamp change. It is very important to note that UV lamps do not “burn out” before they lose disinfecting properties, so changing them on schedule is critical to maintain water safety.
Back in 2008 there was a published report by Global Water Intelligence that came to the following conclusion. One of the fastest growing water treatment technologies is UV water disinfection and purification. The water treatment industry uses a high-powered form of UV light called UV-C or “germicidal UV” to disinfect water. UV water disinfection performance is tied to the first laws of Photochemistry where only the light that is absorbed by a molecule can be effective at producing a photochemical change in the molecule. What this means is that in order for UV Water Treatment systems to work the light must be absorbed by the organism(s) in the water. Then the UV light causes damage to the DNA and RNA structure preventing it form being able to replicate itself. UV Water treatment systems are effective in destroying 99.99% of harmful microorganisms, including E. coli, Cryptosporidium, and Giardia.
Municipal water treatment facilities are looking to this new form of water treatment as a viable green alternative for public water treatment. Public officials are looking to avoid water contamination problems with public sources such as the 1993 Cryptosporidium outbreak in Milwaukee, WI. Currently California is leading the charge with UV water treatment implementation. Public elected officials, regional labor leaders, and the San Francisco Public Utilities Commission (SFPUC) have recently broke ground on what will be California’s largest ultraviolet (UV) water disinfection facility when completed in 2011.
Johnson is an avid hiker. His book is loaded with tips and advice, especially for those who are looking for resourceful ways to improve their skills and trek even deeper into remote areas of the globe.
Here’s Johnson on the SteriPen’s benefits:
Ultraviolet (UV) radiation has been used for years to purify water, but the Steri-Pen is the first truly portable device I know of to use the principle to treat water without chemicals. About 7 inches long and weighing 6 ounces, the Steri-Pen uses four AA batteries to light a germicidal UV lamp ( liquid level sensors prevent the UV lamp from lighting unless it is fully submerged in water). After collecting and straining a pint of clear water, you can activate the Steri-Pen with a button-pushing sequence, and stir the tip of the pen in the water for thirty-eight to forty-eight seconds. A microcomputer determines the exact duration of the UV dosage, and a small LED (light-emitting diode) light indicates when the treatment is complete. That’s all there is to it.
So, before you next venture into the woods or dessert, make sure to have a SteriPen. It’s the mobile device that will clean your water and keep you going longer.
Ultraviolet technology can be more effective than chemicals in destroying certain waterborne contaminants without altering the taste of water. This makes it a practical process for treating water used for drinking and food preparation. UV light penetrates germs and disrupts their DNA, preventing them from multiplying. UV disinfection has many advantages over other methods because UV systems can be compact and easy to install. UV does not require holding tanks or long reaction times. UV can also be used in conjunction with other water treatment methods.
The UV disinfection process is quick, but different germs require different amounts of UV energy, or dosages to be destroyed. UV units should be installed after any water pre-treatment process, just before the cold and hot branch lines. If in doubt about the size of a UV unit that is needed, always use a larger unit rather than a smaller unit. Normally an 8 gpm UV unit will be adequate for an average size house. UV should be installed as close as possible to the dispensing point. UV disinfection systems like Sterilight and Pura are very quickly gaining ground on other conventional disinfection processes because it is effective, environmentally friendly and economical. UV does not change the taste of water nor does it add anything to it. It is the ideal choice for disinfecting water.