What’s in your tap water?

There is no such thing as “pure” water. As it moves through the water cycle, water picks up minerals, plant matter, and man-made contaminants that eventually end up in lakes and streams, where many cities get their drinking water.

While the water treatment process removes many of these compounds, it’s impossible to remove them all. 

These compounds many be found in common drinking water.  

The level of the compound contaminant is that matters.

Biological Compounds, such as viruses and bacteria, may come from septic systems, agricultural livestock operations, and wildlife. 

Inorganic compounds, such as salts and metals, which can be naturally occurring or the result of storm water runoff, industrial or domestic wastewater discharges, oil and gas. 

Pesticides and herbicides, which may come from a variety of sources such as agriculture, runoff, and residential uses. 

Organic compounds, including synthetic and volatile organics, which are by-products of industrial processes and petroleum production, can also come from gas stations, runoff, and septic systems.

Radioactive materials, which can be naturally occurring or be the result of oil and gas production and mining activities.

To make sure tap water is safe to drink, the US EPA prescribes regulations that limit the amount of certain contaminants in water provided by public water systems. US Food and Drug Administration (FDA) regulations establish limits for compounds in bottled water.
 

Definitions for Water Quality Table

Maximum Contaminant Level Goal (MCLG)
The level of a contaminant in drinking water below which there is no known or expected risk to health. MCLG’s allow for a margin of safety.

Maximum Contaminant Level
(MCL)
The highest level of a contaminant that is allowed in drinking water. MCL’S are set as close to the MCLGs as feasible using the best available treatment technology.

Action Level (AL)
The concentration of a contaminant, which, if exceeded, triggers treatment or other requirements that a water System must follow.

Treatment Technique (TT)
A required process intended to reduce the level of a contaminant in drinking water

Maximum Residual Disinfectant Level (MRDL)
The highest level of 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 (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 contamination.

Biological Compounds and Physical Characteristics

Total Coliform Bacteria
A group of bacteria whose presence in water indicates possible contamination with soil or waste
from warm blooded animals.

Turbidity
A measure of the amount of suspended particles in the water (cloudiness); an indicator of overall
water quality and filtration effectiveness.


Inorganic Compounds

Copper
A metal widely used in household plumbing that may corrode into water.

Lead
A metal no longer used in water pipes, but maybe present in  plumbing materials

Nitrates and nitrites are nitrogen-oxygen chemicals that can become a source of pollution
in the form of unwanted nutrients.

Fluoride
A chemical that is naturally occurring in some water sources, particularly groundwater. It is also added to drinking water to help prevent tooth decay.
 

Disinfectants

Chlorine Dioxide
A disinfection agent added in small amounts to disinfect against bacteria.

Chloramine Residual
A compound of chlorine and ammonia that is added in small amounts to treated water to disinfect against bacteria.


Disinfection Byproducts

Total Trihalomethanea (THMs)
A group of chemicals formed when chlorine used to disinfect drinking water reacts with naturally occurring organic and inorganic matter in the water.

Total Haloacetic acids (HAAs)
A group of chemicals formed when chlorine used to disinfect drinking water reacts with naturally  occurring organic and inorganic matter in the water.

Chlorite
A byproduct formed when chlorine dioxide is used to disinfect water.


Organic Compounds

Total Organic Carbon (TOC)
The measure of organic substances in a body of water, mostly from naturally occurring sources such as plant material. TOO has no health effects, but it provides a measurement for the potential formation of disinfection byproducts.


Unregulated Compounds

Sodium
The salt level in water.
 
Cryptosporidium                                                                                                                   A parasite spread through human and animal waste that causes gastrointestinal illness. People with
weakened immune systems are more likely to suffer severe symptoms than healthy individuals.

Giardia
A parasite spread through human and animal waste that causes gastrointestinal illness. People with
weakened immune systems are more likely to suffer severe symptoms than healthy individuals.