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.
Ten contaminants are currently included in Vermont’s Tracking data.
Four are naturally occurring in the environment:
Two are disinfection byproducts:
Four are man-made:
There are three overall categories of public drinking water supply data on Vermont Tracking.
1. Contaminant data for community systems serving 500 people or more
Public community water supplies are systems that serve at least 15 connections or 25 people who live year-round in Vermont. There are more than 450 public community water systems in the state, but the data presented in this category are only for systems that serve more than 500 people. There are about 100 community systems that serve more than 500 people. Most are town or fire district water systems.
For each of these systems, annual data are presented for 10 contaminants, starting in 1999. Data include the mean contaminant concentrations presented on a table, on a state map, on a graph, and as a time trend starting in 1999.
Data also show whether the contaminant concentration has ever exceeded the Environmental Protection Agency’s maximum contaminant level or the Vermont Drinking Water Standard for that contaminant.
2. Number of community water systems and people served by contaminant concentration
These data divide mean concentration levels of each contaminant into categories, and show the number of community water systems and the number of people served by these systems in each category. The mean annual concentration data are presented both by year and by quarter, starting in 1999. Annual data showing the maximum concentration of the contaminant are also presented starting in 1999.
Also included in these data is an estimate of the total number of consumers served by public community water systems. Estimates of the population served are self-reported by each
water system and are typically updated every three to five years depending on system type.
3. Information for all public systems (community, transient and non-transient)
To view this information, the user leaves the Vermont Tracking portal and goes to the Department of Environmental Conservation’s Drinking Water Watch. Drinking Water Watch has comprehensive information for more than 1,600 public systems. The information includes test result data on all EPA and state-regulated contaminants, as well as descriptive information such as the location and operator of the system, system specifications and site visits by regulators.
Three types of public water supply systems are included in Drinking Water Watch:
- Community (C): Systems that serve at least 15 service connections used by year-round residents or regularly serve 25 year-round residents. Examples: towns, fire districts and mobile home parks.
- Non Transient, Non Community (NTNC): Systems that serve at least the same 25 non-residential individuals during six months of the year. Examples: schools, office complexes and businesses with 25 or more employees served by their own water system.
- Transient Non Community (NC): Systems that regularly serve at least 25 non-residential individuals (transient) during 60 or more days per year. Examples: hotels, restaurants and convenience stores served by their own water system.
View Data by clicking here. Choose “Drinking Water - Public” from the drop-down menu.
Private drinking water data are for arsenic and nitrate. Data are presented by town when at least 20 test results for the contaminant were available from the years 2003 to 2014. The test results are displayed on Vermont maps in two ways.
- Percent of tests above the maximum contaminant level (MCL)
The MCL for arsenic is 10 micrograms per liter (µg/L).
The MCL for nitrate is 10 milligrams per liter (mg/L).
- 95th percentile of contaminant concentration
Indicates that 95% of the well results are below this concentration level.
Private water data are also provided on tables that summarize the test results for the period 2003 to 2014 on each contaminant. Categories on the tables are:
- Towns with 20 or More Tests
- Number of Tests
- % Tests Above MCL
- Concentration of Contaminant
- Standard Deviation
- 95th Percentile
- 5th Percentile
Learn more about contaminants and the importance of testing your private water supply from the Environmental Health Spotlight - Private Drinking Water: A User's Guide.
View Data by clicking here. Choose “Drinking Water - Private” from the drop-down menu.