If your water comes from a public or municipal water system, it is regularly tested for contaminants regulated by federal standards, such as microbial pathogens, radioactive elements and organic and inorganic toxic chemicals. However, it is important to note that these tests are conducted at the source. Therefore, the quality of water that utilities create is not necessarily a measure of the quality that reaches your home. Over time pipes age and erode, and often water treatment or distribution systems are breached by unforeseen occurrences that result in boil water alerts.