On average, each person consumes more than a quart of water each day. As a result, contaminated drinking water becomes a significant public health risk. Approximately 90 percent of U.S. residents drink water from regulated community water systems.
In Vermont, about 60 percent of residents drink water from regulated community water systems, while 40 percent draw water from their own private wells or springs. The Vermont Department of Health recommends that homeowners test private water supplies:
- Yearly for coliform bacteria.
- Every five years for inorganic chemicals.
- Every five years for naturally occurring alpha radiation.
Public community water supplies are systems that serve at least 15 connections or serve 25 people. All water systems that fit this designation are tested for bacterial, chemical and radiological contaminants on a regular basis. The U.S. Environmental Protection Agency and the states regulate more than 90 contaminants in public drinking water. Community systems are required to send to their customers yearly Consumer Confidence Reports that contain specific information about sources and testing of their water.
Private water supplies are systems that serve single family homes, duplexes or small groups of homes. Private systems need to be permitted, but after the initial permit, they are monitored and maintained by their owners. It is important for owners to do their own water testing and maintenance to make sure their drinking water remains safe.
How can drinking water become contaminated?
Drinking water can become contaminated through natural or manmade causes. Naturally occurring chemicals such as arsenic or uranium can enter groundwater from bedrock. Humans add chemicals to water both intentionally and by accident. Adding chemicals, such as chlorine, to water to kill disease-causing organisms can produce other potentially harmful chemicals called disinfection by-products or DBPs. Runoff from failing septic systems or animal waste can introduce nitrates or bacteria into water. Plumbing fixtures or piping can leach lead or copper into water.
People can be exposed to contaminants not only by drinking the water, but also by eating foods prepared with the water, breathing water droplets or chemicals released from the water while showering, or by absorbing chemicals through their skin while bathing.