• Safe drinking water should be everybody's goal.drinking fountain image by michael langley from Fotolia.com
  
  Drinking contaminated water leads to a host of deadly or debilitating diseases, including cholera, salmonella poisoning and "Montezuma's Revenge." While many city water supplies are pathogen free, water supplies from questionable sources, such as wells, may not be. The only sure way to make the water safe to drink is by filtration and Ultra Violet light treatment. UV light kills bacteria, and understanding the devices available leads to a greater understanding of water filtration systems.
  
  

Mercury Vapor Lamp

• Mercury vapor lamps are the core component of all UV water treatment systems, regardless of the remaining differences between the systems. The University of Iowa cautions that as time goes on, the effectiveness of the bulb decreases. Unfortunately, the university reports that no manufacturer has a warning system that tells you when the lamp is not providing adequate disinfection. To be on the safe side, lamps should be replaced once a year.
  
  

Quartz Tube System

• Cornell University states that a quartz tube system is typical of water treatment systems. In this setup, a long, thin mercury vapor lamp in encased in a quartz glass tube. A space or gap is present between the light bulb and the inside wall of the tube. The tube has an inlet and an outlet through which water flows. The water flow is kept slow, so the UV radiation has enough time to kill the bacteria before the water flows out of the tube.
  
  

Experimental Systems

• A system was developed at Purdue University that places baffles inside the quartz tube. By inducing a turbulent water flow, the UV light can penetrate deeper into the water. The end result is that more effective disinfecting capabilities are possible with faster water flow through the tube. This is significant for a large water treatment system, such as one that supports a small community. Faster flow equals more water output per hour.