Common Water Tests / Health Effects

For the comprehensive list of contaminants in drinking water go to:

Some common contaminants found in the Delaware, Maryland, DC and Virginia are:

Total Coliform:
Not a health threat in itself, it is used to indicate whether other potentially harmful bacteria may be present.

E. coli:
E. coli is a type of fecal coliform bacteria commonly found in the intestines of animals and humans. E. coli is short for Escherichia coli. The presence of E. coli in water is a strong indication of recent sewage or animal waste contamination. Sewage may contain many types of disease-causing organisms.

E. coli comes from human and animal wastes. During rainfalls, snow melts, or other types of precipitation, E. coli may be washed into creeks, rivers, streams, lakes or groundwater. When these waters are used as sources of drinking water and the water is not treated or inadequately treated, E. coli may end up in drinking water.

Arsenic: Arsenic is a toxic chemical element that is naturally found in the Earth's crust in soil, rocks, and minerals. There is a wide variation in the levels of arsenic found in drinking water systems and private water supplies across the Nation. In 2001 the U.S. EPA lowered the drinking water standard for arsenic to 10 parts per billion. Some people who drink water containing arsenic in excess of EPA's standard over many years could experience skin damage or problems with their circulatory system, and may have an increased risk of getting cancer.

Lead: AL = 15 ppb, MCL = 15 ppb
The health effects of lead are most severe for infants and young children. For infants and young children, exposure to high levels of lead in drinking water can result in delays in physical or mental development. For adults, it can result in kidney problems or high blood pressure. Although the main source exposure to lead are ingesting paint chips and inhaling dust, EPA estimates that 10 to 20 percent of human exposure to lead may come from lead in drinking water. Infants who consume mostly mixed formula can receive 40 to 60 percent of their exposure from lead in drinking water.
Typically, lead gets into your drinking water after the water leaves your local treatment plant or your well. The source of lead in your home's water is most likely pipe or solder in your home's own plumbing or from lead service lines entering your home. This is why it is important to get a 1st draw and a flushed test of your water.

Copper: AL = 1.3 ppm, MCL = 1.3 ppm
Short and long-term effects. Copper is an essential nutrient, required by the body in very small amounts. However, EPA has found copper to potentially cause the following health effects when people are exposed to it at levels above the Action Level. Short periods of exposure can cause gastrointestinal disturbance, including nausea and vomiting. Use of water that exceeds the Action Level over many years could cause liver or kidney damage. People with Wilson's disease may be more sensitive than others to the effect of copper contamination and should consult their health care professional.
Since copper contamination generally occurs from corrosion of household copper pipes, it cannot be directly detected or removed by the water system. Instead, EPA is requiring water systems to control the corrosiveness of their water if the level of copper at home taps exceeds an Action Level.

Nitrates: AL = 10 ppm, MCL = 10 ppm
Infants below the age of six months who drink water containing nitrate in excess of the MCL could become seriously ill and, if untreated, may die. Symptoms include shortness of breath and blue-baby syndrome. Short-term: Excessive levels of nitrate in drinking water have caused serious illness and sometimes death. The serious illness in infants is due to the conversion of nitrate to nitrite by the body, which can interfere with the oxygen-carrying capacity of the child's blood. This can be an acute condition in which health deteriorates rapidly over a period of days. Symptoms include shortness of breath and blueness of the skin. Long-term: Nitrates and nitrites have the potential to cause the following effects from a lifetime exposure at levels above the MCL: diuresis, increased starchy deposits and hemorrhaging of the spleen.

Turbidity: MCL = 10 NTU

Turbidity is a measure of the cloudiness of water. It is used to indicate water quality and filtration effectiveness (e.g. whether disease causing organisms are present). Higher turbidity levels are often associated with higher levels of disease causing microorganisms such as viruses, parasites and some bacteria.

Iron: SMCL = 0.3 mg/L
Iron makes up about five percent of the earth's crust and can exist as soluble ferrous iron or as the relatively insoluble ferric form found in water. Soluble ferrous iron is found in ground water, in anaerobic reservoirs, in dead-ends in water distribution systems, and in scale (hard mineral coatings) within pipes. When soluble ferrous iron is exposed to oxygen or to a disinfectant during water treatment, it oxidizes to the relatively insoluble iron (i.e., suspended colloidal and particulate iron) that is responsible for discolored water. The primary sources of iron in drinking water are natural geologic sources as well as aging and corroding distribution systems and household pipes. Iron-based materials, such as cast iron and galvanized steel, have been widely used in our water distribution systems and household plumbing.

Effects of Iron on Human Health, Water Quality, and Distribution System Infrastructure
Iron is an essential mineral for human health in small concentrations (iron deficiency can lead to anemia). Unlike lead and copper, ingesting iron from drinking water is not directly associated with adverse health effects; although, trace impurities and microorganisms that are absorbed by iron solids may pose health concerns.

The effects associated with iron contamination can be grouped into two categories:

Aesthetic effects are undesirable tastes or odors. Iron in quantities greater than 0.3 milligrams per liter (mg/L) in drinking water can cause an unpleasant metallic taste and rusty color. Taste is a useful indicator of water quality even though taste-free water is not necessarily safe to drink. Taste is also an indicator of the effectiveness of different kinds of treatments that effectively remove iron from drinking water, such as water softening or reverse osmosis treatment systems. Elevated levels of iron in drinking water can also cause a rusty color that can stain laundry or household. Discolored water is one of the most frequent consumer complaints about drinking water.

Physical effects are damages to water equipment and reduced effectiveness of treatment for other contaminants that may present added costs to operations for water utilities. Corrosivity and staining related to corrosion not only affect the aesthetic quality of water, but may also result in distribution system problems. Among other things, corrosion of distribution system pipes can produce sediment or loose deposits that block water flow.

AL: Action Level

MCL: Maximum Contaminant Level

SMCL: Secondary Maximum Contaminant Level