Approximately 15 percent of the population relies on private wells for their drinking water in the United States today. Then there are those that rely on other surface water sources such as lakes, rivers, and some even use rain runoff collection systems, as well, for their drinking water. The quality of these sources can vary from day-to-day however, so this means in many cases, you would need a water purification system in place to remove/destroy contaminates.
One way to destroy or to inactivate microorganisms is by using Ultraviolet light. This is a proven disinfection method that uses short-wavelength ultraviolet light to destroy and/or to inactivate contaminates.
As many of you know, water in a survival situation can be purified using just the sun’s rays. Water is first filtered or the debris is allowed to settle in a clear container, and then is placed in direct sunlight for 6 hours or more. The water is disinfected by the sun’s rays, UV rays. UV systems using bulbs or lamps installed in your home can produce the same effect, but with greater and more reliable intensity.
How It Works
A typical system is set up so that water flows through a vessel that houses a UV lamp or bulb. As the water passes through, the microorganisms are exposed to intense ultraviolet light energy, which causes damage to genetic molecules (nucleic acids, DNA or RNA) needed for reproductive functions.
The damage prevents the microorganism from multiplying or replicating in a host such as you. Because the microorganism cannot multiply, no infection can occur. Disinfection of water is achieved when the UV light causes “microbial inactivation” (2008).
Simply put, ultraviolet light with enough intensity creates energy, which reaches the nucleus of microorganisms and jumbles up their DNA.
Remember though, a UV water disinfection system is not a filtration system. It will not remove any debris from the water, so it is important that a quality filtration system is in place along with a UV system.
Typically, a filtration system that you use would have to remove any particles larger than 5 microns. Larger particles can block the UV light, and so would act as a shield, and not allow the light to disinfect the water.
A UV system is chemical free, does not add odor or taste, and is more effective than sodium hypochlorite (bleach) in destroying Cryptosporidium and Giardia.
A UV system can control one faucet, for example, or the entire house with little maintenance involved. You would be expected to replace bulbs according to the manufactures’ specifications. Usually the bulbs need to be replaced at least once a year. As the bulbs age the intensity is reduced, and thus, could compromise the quality of your water. It is recommended that you use a quality water tester to verify the purity of your drinking water.
It is important that you research carefully before installing a system, because it needs to be sized correctly. They are sized according to wattage and your usage. The typical home could probably get by with a system that can disinfect 10 gallons per minute. Larger units for more gallons per-minute would require more wattage of course.
It is better to install an oversized unit than an undersized one, if there is any doubt about what size to use. To small of a unit for the flow rate may result in inadequate/unsafe disinfection.
To make your drinking water safe to drink, the water must be exposed to a sufficient intensity for the correct amount of time.
The USDA states that for a UV system to be effective, it should provide at a minimum, 16,000 microwatts per centimeter square.
Generally, a UV disinfection unit is composed of a lamp or bulb, power supply, and electronic ballast. You can install a system yourself, but you have to ensure your pipes are properly sanitized prior to installation so your water is not once again contaminated by your pipes past the UV system.
Disadvantages of Using an UV System
UV light is not as effective against viruses as chlorine is. The intensity of the UV light needed to kill viruses would be higher than practical for most households. For those that rely on a private well, for example, can use chlorine in combination with a UV system to ensure viruses are destroyed. Your water today in your well might be safe, but runoff and other surface to ground sources can contaminate your private well at any time.
Another disadvantage is the need for a quality water filtration system, and this is very important. Debris in the water can essentially render a UV system ineffective without your knowledge, so the filtration system would need constant maintenance, and verification that it is working properly.
(2008). Retrieved 2015, from http://www5.agr.gc.ca/resources/prod/doc/terr/pdf/uv_tech_bull_e.pdf