It is important to know the source of your drinking water. The first question should be: does my water come from a Public Water Supply (City Water) or a Private Water System (Well Water or Spring that "You" control)? The United States Environmental Protection Agency (USEPA) has established drinking water standards for public water supplies. However, Private Systems are not regulated by the EPA and most states.
A public water supply is defined as "a system which provides water to the public for human consumption and which has at least 15 service connections or regularly services an average of at least 25 individuals daily at least 60 days out of the year". If your source is not a public water supply, you are on a private system. Most public water supplies may also be known as "City Water", because they are typically managed by an Association, Authority, Water Company, Utility, or other entity. These systems may use a combination of surface water reservoirs, lakes, and streams. Public water supply systems normally have some form of pretreatment and in most cases this would include some form of disinfection and corrosion control with the water containing a disinfection residue to inhibit microbiological regrowth in the distribution system. Public water supply systems can be serviced by well water, streams, lakes, reservoirs, springs, and even the ocean (after extensive treatment). In fact, we have worked in the country of Aruba and their drinking water starts as "seawater" or "wells" along the shoreline; the seawater is treated using a combination of systems to produce a high-quality drinking water source.
In general, most private systems are normally serviced by on-site drilled and cased water wells, but in some cases these private systems can be serviced by rainfall capture, streams, lakes, springs, or old hand-dug wells. Private systems do not usually have significant treatment systems beyond basic particle filtration and perhaps UV disinfection. If you have your own private water well or you share a well with less than 25 people or less than 15 service connections, you have a private "Well Water" system.
Keystone Clean Water Team
The Keystone Clean Water Team is a Pennsylvania-based non-profit 501C3 organization whose mission is to educate private well owners about the basics on wells, water, septic systems, and other environmental issues. One of their goals is to prevent illnesses that can be acquired from having a private, unregulated water system and to "Get The Waters Tested". Learn more about the mission of the Keystone Clean Water Team at www.pacleanwater.org