How Do Contaminants Get in the Water Supply ?
The sources of drinking water ( both tap water and bottled water ) include rivers , lakes , streams , ponds , reservoirs , springs , and wells . As water travels over the surface of the land or through the ground , it dissolves naturally occurring minerals and , in some cases , radioactive material , and can pick up substances resulting from the presence of animals or from human activity .
Contaminants that may be present in source water include :
Inorganic contaminants : Includes salts and metals , which can be naturally occurring or result from urban stormwater runoff , industrial or domestic wastewater discharges , oil and gas production , mining , or farming .
Microbial contaminants : Includes viruses and bacteria , and may come from sewage treatment plants , septic systems , agricultural livestock operations and wildlife .
Organic chemical contaminants : Includes synthetic and volatile organic chemicals , which are by-products of industrial processes , and can also come from gas stations , urban stormwater runoff and septic systems .
Pesticides and herbicides : Come from a variety of sources such as agriculture , urban stormwater runoff and residential uses .
Radioactive contaminants : Can be naturally occurring or be the result of oil and gas production and mining activities .
Contaminant Regulations
To ensure that tap water is safe to drink , the EPA prescribes regulations , which limit the amount of certain contaminants in water provided by public water systems . The U . S . Food and Drug Administration ( FDA ) regulations establish limits for contaminants in bottled water , which must provide the same protection for public health .
Ensuring Water is Safe to Drink
Your water is monitored for many substances on a strict sampling schedule to ensure it meets specific health standards and maintains the high-quality that residents know and expect .
The following tables list substances that may be found in your tap water , as well as the U . S . Environmental Protection Agency ’ s ( EPA ) established acceptable levels of these contaminants .
Keep in Mind
• The state allows some contaminants to be monitored less often than once per year because the concentration of these elements do not change frequently . In these instances , the most recent sample data is included along with the year in which the sample was taken .
• Drinking water , including bottled water , may reasonably be expected to contain at least small amounts of some contaminants . The presence of contaminants does not necessarily indicate that the water poses a health risk . More information about contaminants and potential health effects can be obtained by calling the Environmental Protection Agency ’ s Safe Drinking Water Hotline at 1-800-426-4791 .
Understanding Our Test Results
Below are definitions of the terms used in this report .
Action Level ( AL ): The concentration of a contaminant which , if exceeded , triggers treatment or other requirements that a water system must follow .
Contaminant : Any unwanted physical , chemical , biological or radiological substance or matter in water .
Maximum Contaminant Level or MCL : The highest level of a contaminant that is allowed in drinking water . MCLs are set as close to the MCLGs as feasible using the best available treatment technology .
Maximum Contaminant Level Goal or MCLG : The level of a contaminant in drinking water below which there is no known or expected risk to health . MCLGs allow for a margin of safety .
Maximum Residual Disinfectant Level or MRDL : The highest level of a disinfectant allowed in drinking water . There is convincing evidence that addition of a disinfectant is necessary for control of microbial contaminants .
Maximum Residual Disinfectant Level Goal or MRDLG : The level of a drinking water disinfectant below which there is no known or expected risk to health . MRDLGs do not reflect the benefits of the use of disinfectants to control microbial contaminants .
N / A : Not applicable ND : Not detected and indicates that the substance was not found by laboratory analysis . Picocurie Per Liter ( pCi / L ): Measure of the radioactivity in water .
Parts Per Billion ( PPB ) or Micrograms Per Liter ( mg / l ): One part by weight of analyte to 1 billion parts by weight of the water sample .
Parts Per Million ( PPM ) or Milligrams Per Liter ( mg / l ): One part by weight of analyte to 1 million parts by weight of the water sample .
What is PPM ? Many of the utilities ’ test results are reported as “ parts per million ” ( ppm ) or “ parts per billions ( ppb ).
PPM ( Parts Per Million )
Means one part per 1,000,000 parts . This is equivalent to two thirds of a gallon in an Olympic-sized swimming pool which holds 660,000 gallons .
PPB ( Parts Per Billion )
Means one part per 1,000,000,000 parts . This is equivalent to half of a teaspoon in an Olympicsized swimming pool .