In the US and other industrialized countries, a variety of disinfectants are used to kill algae and bacteria in water for drinking. While this greatly reduces the incidence of waterborne illnesses, it causes another long-term health problem.
When disinfectants of any kind react with bacterium or other living organisms, byproducts are created. For example, when chlorine or chloramines are used, trihalomethanes are created. Exposure to trihalomethanes is known to cause an increased risk of cancer. Researchers feel that exposure to any disinfection byproducts are accompanied by the same risks.
Trihalomethanes and other disinfection byproducts build up inside of the waterlines that lead to your home. When the waters are heated or boiled, the chemicals enter the air of your home. Initially, it was thought that the only risk was through consumption and that the risks were low. Now it is known that there is also a risk from inhalation and dermal absorption during baths or showers.
It is important to protect your health and your family's health from these chemicals. You can do that by installing a water purifier on your kitchen tap and another on your showerhead. You will need to check the company's product performance data to be sure the purifier removals trihalomethanes.
Public treatment facilities are required to notify consumers when bacteria water contamination is a threat. This is usually due to some kind of failure in the disinfecting process, although flooding and other natural disasters can cause the problem by overwhelming the system.
When you are informed of this kind of problem, you must boil everything that you drink or buy bottled. In my opinion, the only time you should buy bottled is during a natural disaster, when it is absolutely necessary. In all other situations, your own tap water is a healthier choice.
Bacteria water contaminations are reliably rare, but another illness-causing pathogen may be present in any source at any time. Facilities may not be able to notify their consumers in the event of cyst contamination, because it can happen at any time and they test on an infrequent basis.
Cysts can also be removed by home water purifiers that include a sub-micron filtration step. It is particularly important that people with weakened immune systems buy and install a water purifier that includes the necessary step, because the illness caused by the parasite can kill them.
That's what you need to know about bacteria in water. It's not usually something to worry about, but you do have to take steps to protect your health from the byproducts of disinfection.