Why use UV?: Low power UV is extremely effective at inactivating bacteria, viruses, and dangerous parasitic protozoa, like Cryptosporidium and Giardia, which can be present in water supplies from all sources. In addition, Cryptosporidium and Giardia are extremely difficult to eradicate using the more familiar technique of chlorine disinfection, requiring a concentration some 25 times that found in a public swimming pool! UV disinfection, being a purely physical process, adds no by-products to the water, unlike chlorine which can react with organic matter to produce potentially harmful chlorinated compounds (known as “THM’s”). The almost instantaneous inactivation of microorganisms by UV removes the need for contact vessels, chemical feed pumps and hazardous chemical storage, allowing for a very simple, compact, in-line installation. Once a microorganism is inactivated, it is unable to reproduce (as shown in a “colony count” bacteriological test) and is therefore incapable of causing illness or spreading disease.
Rural wells can be impacted by degradation of groundwater quality caused by failing septic systems, farm run-off, and many other sources. Groundwater in the aquifer is continuously moving, which can make contamination intermittent and completely unpredictable. The water can test “good” today but fail tomorrow. Temporary sickness or worse is often blamed on contaminated food when, in fact, contamination of the water supply is frequently the cause, not only through direct ingestion but also by contamination of food that has been washed with contaminated water. Similarly, water drawn from lakes, streams, rivers and reservoirs is often contaminated with animal fecal matter which can give rise to the presence of Cryptosporidium and Giardia parasites in particular. The occurrence of Cryptosporidium in surface drinking water supplies is recognized as a significant threat to public health throughout the world. In contrast with disinfection by the addition of chlorine, these water-borne parasitic organisms are easily eradicated by the application of UV disinfection.
UV is not a new technology: UV (ultra-violet) disinfection is an established technology supported by decades of use in applications from drug manufacturing to waste water treatment. The first drinking water disinfection application took place in Marseilles, France as far back as 1910 and considerable research has since been carried out on the inactivation of microorganisms by the application of UV light.