Common Water Tests / Health Effects
For the comprehensive list of contaminants in drinking water go
to: https://www.epa.gov/dwstandardsregulations
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
