If your family gets drinking water from a private well, do you
know if your water is safe to drink? What health risks could you
and your family face? Where can you go for help or advice? EPA
regulates public water systems; it does not have the authority
to regulate private drinking water wells. Approximately 15
percent of Americans rely on their own private drinking water
supplies, and these supplies are not subject to EPA standards,
although some state and local governments do set rules to
protect users of these wells. Unlike public drinking water
systems serving many people, they do not have experts regularly
checking the waters source and its quality before it is sent to
the tap. These households must take special precautions to
ensure the protection and maintenance of their drinking water
There are three types of private drinking water
wells: dug, driven, and drilled. Proper well construction and
continued maintenance are keys to the safety of your water
supply. Your state water-well contractor licensing agency, local
health department, or local water system professional can
provide information on well construction. The well should be
located so rainwater flows away from it. Rainwater can pick up
harmful bacteria and chemicals on the lands surface. If this
water pools near your well, it can seep into it, potentially
causing health problems. Water-well drillers and pump-well
installers are listed in your local phone directory. The
contractor should be bonded and insured. Make certain your
ground water contractor is registered or licensed in your state,
if required. If your state does not have a
licensing/registration program contact the National Ground Water
Association. They have a voluntary certification program for
contractors. (In fact, some states use the Associations exams as
their test for licensing.) For a list of certified contractors
in your state contact the Association at (614) 898-7791 or (800)
551-7379. There is no cost for mailing or faxing the list to
To keep your well safe, you must be sure possible sources of
contamination are not close by. Experts suggest the following
distances as a minimum for protection farther is better:
Septic Tanks, 50 feet
Livestock yards, Silos, Septic Leach Fields, 50 feet
Petroleum Tanks, Liquid-Tight Manure Storage and Fertilizer
Storage and Handling, 100 feet
Manure Stacks, 250 feet
Many homeowners tend to forget the value of good maintenance
until problems reach crisis levels. That can be expensive. Its
better to maintain your well, find problems early, and correct
them to protect your wells performance. Keep up-to-date records
of well installation and repairs plus pumping and water tests.
Such records can help spot changes and possible problems with
your water system. If you have problems, ask a local expert to
check your well construction and maintenance records. He or she
can see if your system is okay or needs work.
Protect your own well area. Be careful about storage and
disposal of household and lawn care chemicals and wastes. Good
farmers and gardeners minimize the use of fertilizers and
pesticides. Take steps to reduce erosion and prevent surface
water runoff. Regularly check underground storage tanks that
hold home heating oil, diesel, or gasoline. Make sure your well
is protected from the wastes of livestock, pets, and wildlife.
Dug wells are holes in the ground dug by shovel or backhoe.
Historically, a dug well was excavated below the groundwater
table until incoming water exceeded the diggers bailing rate.
The well was then lined (cased) with stones, brick, tile, or
other material to prevent collapse. It was covered with a cap of
wood, stone, or concrete. Since it is so difficult to dig
beneath the ground water table, dug wells are not very deep.
Typically, they are only 10 to 30 feet deep. Being so shallow,
dug wells have the highest risk of becoming contaminated.To
minimize the likelihood of contamination, your dug well should
have certain features. These features help to prevent
contaminants from traveling along the outside of the casing or
through the casing and into the well.
Dug Well Construction Features
The well should be cased with a watertight material (for
example, tongue-and-groove precast concrete) and a cement grout
or bentoniteclay sealant poured along the outside of the casing
to the top of the well.
The well should be covered by a concrete curb and cap that
stands about a foot above the ground.
The land surface around the well should be mounded so that
surface water runs away from the well and is not allowed to pond
around the outside of the wellhead.
Ideally, the pump for your well should be inside
your home or in a separate pump house, rather than in a pit next
to the well.
Land activities around a dug well can also contaminate it. While
dug wells have been used as a household water supply source for
many years, most are relics of older homes, dug before drilling
equipment was readily available or when drilling was considered
too expensive. If you have a dug well on your property and are
using it for drinking water, check to make sure it is properly
covered and sealed. Another problem relating to the shallowness
of a dug well is that it may go dry during a drought when the
ground water table drops.
Like dug wells, driven wells pull water from the water-saturated
zone above the bedrock. Driven wells can be deeper than dug
wells. They are typically 30 to 50 feet deep and are usually
located in areas with thick sand and gravel deposits where the
ground water table is within 15 feet of the grounds surface. In
the proper geologic setting, driven wells can be easy and
relatively inexpensive to install. Although deeper than dug
wells, driven wells are still relatively shallow and have a
moderate-to-high risk of contamination from nearby land
Driven Well Construction Features
Assembled lengths of two inches to three inches diameter metal
pipes are driven into the ground. A screened well point located
at the end of the pipe helps drive the pipe through the sand and
gravel. The screen allows water to enter the well and filters
The pump for the well is in one of two places: on
top of the well or in the house. An access pit is usually dug
around the well down to the frost line and a water discharge
pipe to the house is joined to the well pipe with a fitting.
The well and pit are capped with the same kind of large-diameter
concrete tile used for a dug well. The access pit may be cased
with pre-cast concrete.
To minimize this risk, the well cover should be a tight-fitting
concrete curb and cap with no cracks and should sit about a foot
above the ground. Slope the ground away from the well so that
surface water will not pond around the well. If there's a pit
above the well, either to hold the pump or to access the
fitting, you may also be able to pour a grout sealant along the
outside of the well pipe. Protecting the water quality requires
that you maintain proper well construction and monitor your
activities around the well. It is also important to follow the
same land use precautions around the driven well as described
under dug wells.
Drilled wells penetrate about 100-400 feet into the bedrock.
Where you find bedrock at the surface, it is commonly called
ledge. To serve as a water supply, a drilled well must intersect
bedrock fractures containing ground water.
Drilled Well Construction Features
The casing is usually metal or plastic pipe, six
inches in diameter that extends into the bedrock to prevent
shallow ground water from entering the well. By law, the casing
has to extend at least 18 feet into the ground, with at least
five feet extending into the bedrock. The casing should also
extend a foot or two above the grounds surface. A sealant, such
as cement grout or bentonite clay, should be poured along the
outside of the casing to the top of the well. The well is capped
to prevent surface water from entering the well.
Submersible pumps, located near the bottom of the well, are most
commonly used in drilled wells. Wells with a shallow water table
may feature a jet pump located inside the home. Pumps require
special wiring and electrical service. Well pumps should be
installed and serviced by a qualified professional registered
with your state.
Most modern drilled wells incorporate a pit less adapter
designed to provide a sanitary seal at the point where the
discharge water line leaves the well to enter your home. The
device attaches directly to the casing below the frost line and
provides a watertight subsurface connection, protecting the well
from frost and contamination.
Older drilled wells may lack some of these sanitary features.
The well pipe used was often a tight, 10- or 12- inches in
diameter, and covered with a concrete well cap either at or
below the grounds surface. This outmoded type of construction
does not provide the same degree of protection from surface
contamination. Also, older wells may not have a pit less adapter
to provide a seal at the point of discharge from the well.
Hydrofracting A Drilled Well
Hydrofracting is a process that applies water or
air under pressure into your well to open up existing fractures
near your well and can even create new ones. Often this can
increase the yield of your well. This process can be applied to
new wells with insufficient yield and to improve the quantity of
How can I test the quality of my private drinking water
Consider testing your well for pesticides, organic chemicals,
and heavy metals before you use it for the first time. Test
private water supplies annually for nitrate and coliform
bacteria to detect contamination problems early. Test them more
frequently if you suspect a problem. Be aware of activities in
your watershed that may affect the water quality of your well,
especially if you live in an un-sewered area.
In addition to the immediate area around your
well, you should be aware of other possible sources of
contamination that may already be part of your community or may
be moving into your area. Attend any local planning or appeal
hearings to find out more about the construction of facilities
that may pollute your drinking water. Ask to see the
environmental impact statement on the project. See if
underground drinking water sources has been addressed. If not,