Common Water Quality Problems
Arsenic is a naturally occurring element
found in soil and rock and under certain conditions can be released into
groundwater and enter wells. Elevated levels of arsenic have been
found in a number of wells throughout the state with the majority of
these being reported in northeastern Wisconsin. Because arsenic is a
known carcinogen, the State of Wisconsin has recently lowered the
allowable level of arsenic in drinking water to 10 micrograms per liter
(ug/L, also called parts per billion or ppb).
For the most up to date information on arsenic in drinking water visit the Wisconsin DNR arsenic page.
Coliform bacteria are one of the most common problems in Wisconsin's
private wells. As many as 25% of the private well samples tested
annually are unsafe because of the presence of coliform bacteria.
Increased levels of copper in drinking water
is caused by corrosive water and the dissolution of copper plumbing.
Levels of copper in drinking water greater than 1.3 milligrams per liter
(mg/L, also called parts per million or ppm) may cause digestive
Hardness and Water Softeners
Hard water is caused when water comes in
contact with rocks such as limestone and dolomite which contain calcium
and magnesium. While hard water is not a health concern, excessive
amounts of water hardness can cause lime or scale build-up in pipes and
reduce the effectiveness or life of your plumbing. Water softeners are a
common and effective treatment device for homes with water hardness
Although iron in drinking water is not a health concern,
concentrations over 0.3 milligrams per liter can cause undesirable taste
and discoloration problems. Water high in iron are also susceptible to
Not naturally occurring in Wisconsin groundwater at levels of
health concern. Found in water supplies with lead solder or pipes,
especially when water is soft or corrosive. While lead is never
desirable, concentrations greater than 15 micrograms per liter (15 ug/L
also known as parts per billion or ppb) can cause brain, nerve, and
kidney damage, especially in young children.
Nitrate nitrogen (commonly referred to as nitrate) is one of the
most common contaminants found in Wisconsin groundwater. Approximately
12% of private wells in the state exceed the safe drinking water
standard of 10 milligrams per liter (mg/L, also called parts per million
or ppm) for nitrate nitrogen.
A pesticide is any substance used to control or repel unwanted
pests and includes insecticides, herbicides, and fungicides. When
pesticides are spilled, disposed of, or applied on the soil, some amount
can be carried into groundwater and your private well. There are many
pesticides and the effects of many pesticides on health are not known.
If you suspect contamination or live close to areas where pesticides are
used it is always a good idea to have your water tested.
Volatile Organic Chemicals (VOCs)
Other Useful Extension Bulletins on Drinking Water Issues