Most of the general public associates tap water with the chemical chlorine. All municipalities add chlorine to the tap water and maintain a certain level of chlorine in the water. Depending on certain conditions, this can sometimes add a somewhat acrid smell to your municipal tap water.
The general public perception is that chlorine is a bad thing. People often wonder why their water has to have chlorine in it, and often complain about the levels. Companies selling bottled water and home water treatment devices play on and elevate that misconception to their own end to sell more product and make more money.
A perception of chlorine as a bad thing cannot be farther from the truth. Chlorine is the most important chemical that is used in water treatment today.
The discovery of chlorine is one of the most important in the history of water treatment. One of the first known uses of chlorine in drinking water was in 1850 in London, England. There was an outbreak of cholera that was connected to a certain area in London, where other areas were not affected. A gentleman by the name of John Snow disinfected the shared water supply and the cholera outbreak stopped. Indeed, with the advent of the use of chlorine in water treatment, typhoid fever was completely eliminated in the United States by the 1950′s.
Chlorine is a potent disinfectant. Through over one-hundred years of research, experimentation and optimization, the proper use of chlorine has eliminated almost all of the water related diseases in the free world today.
Chlorine is used in two ways to treat municipal water. Firstly, it is used in a process called primary disinfection. Depending on the water source, the water plant will have to reduce and eliminate most of the dirt and debris from the water supply using methods such as sedimentation and filtration. They then will apply an amount of chlorine to the water using an optimized method called contact time. Plant operators are careful to take into account factors such as water temperature, pH balance, the amount of water their municipality needs among other things, and then add a known amount of chlorine to tanks which will let the chlorine contact with the water for a pre-determined minimum time frame. The general formula for contact time is the longer the water can be in contact with the chlorine, the less chlorine is needed to achieve disinfection of the water supply.
The second use of chlorine is a process called secondary disinfection. Secondary disinfection is a process where there is a chlorine residual left or added to the water leaving the plant. This ensures that it keeps the distribution system clean and free from bacterial regrowth, as well as protecting it from main breaks and other potential intrusions into the water system.
Municipalities have been using other methods of primary disinfection such as ultraviolet irradiation, ozone, and chlorine dioxide among other things. However, no disinfectant has been as effective, succesful, and long lasting as chlorine for secondary disinfection. Indeed, most regulatory bodies will allow municipalites to run with a number of primary disinfection technologies, but all must use chlorine as a secondary disinfectant.
The level of chlorine coming out of your tap is so small, it presents no health hazards to you. The only hazard that the chlorine in your water presents is to acute and potentially deadly waterborne diseases like E.Coli, Typhoid, Giardiosis, and Cholera just to name a few.
Always remember that when you turn on your tap, your municipal water is safe to drink thanks to a wonderful chemical we call chlorine. Without a small amount of chlorine, water born illness would be a fact of life instead of just a distant memory.
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