You do need to know simply because you not only drink tap water, but we bath, clean and cook with it. And although the EPA established levels concerning MCLs (Maximum Contaminant Levels) for public water sources, drinking water safety cannot be taken for granted.
The fact is your water may be just fine. However, drinking water comes from a variety of sources and the question of whether or not your tap water is safe will depend on many situations. But safe or not, do you really want to gamble on regulation taking care of your health without ever knowing what is reaching your supply? Let's just take a quick look at some facts.
The source of tap water is either from wells or surface water that includes rivers, lakes or reservoirs. Then it goes through the process of chlorination which is a method of purification that adds the element chlorine to water to make it fit for human consumption. However, chlorination doesn't kill off everything and we still need to deal with lead, chemicals from agriculture, arsenic and even rocket fuel!
OK, if that doesn't move you to check yourself, maybe you figure bottled water is the alternative. But you might be interested to know that the U.S. Food and Drug Administration (FDA), under the Federal Food, Drug, and Cosmetic Act, regulates bottled water as a packaged food product. What this means is that bottled water is not necessarily safer than your tap water. Most health professionals will say that if tap water is available it is probably equally as good as bottled, not to mention the environmental impact bottled water has on environment.
In general, most families do not need to worry about the safety of their tap water. Although testing and purchasing the correct water filter for your home will allow you to insure healthy drinking water for your family, the Environmental Protection Agency's (EPA) regulation of the public water supply is extensive, well enforced and tested frequently. However, If you have a private well, the EPA does not regulate the quality of the water and it is up to you, the homeowner, to analyze, test and maintain your drinking water supply.
So if you are thinking "What is in MY tap water?", there are many sources available to answer this question. You can start with the EPA (link below ) where there is a lot of information and links to reports and states participating in the "Drinking Water Watch".