United States
Environmental Protection
Agency
Office of Water
(4607)
EPA815-F-99-007
October 1999
RADON IN DRINKING WATER:
Questions and Answers
F«A«OT«S«H«E«E«T
What is radon?
Radon is a gas that has no color, odor, or taste
and comes from the natural radioactive
breakdown of uranium in the ground. You can
be exposed to radon by two main sources: (1)
radon in the air in your home (frequently called
"radon in indoor air") and (2) radon in drinking
water. Radon can get into the air your breathe
and into the water you drink. Radon is also
found in small amounts in outdoor air.
Most of the radon in indoor air comes from soil
underneath the home. As uranium breaks
down, radon gas forms and seeps into the
house. Radon from soil can get into any type
of building - homes, offices, and schools - and
build up to high levels in the air inside the
building.
Radon gas can also dissolve and accumulate
in water from underground sources (called
ground water), such as wells. When water that
contains radon is used in the home for
showering, washing dishes, and cooking,
radon gas escapes from the water and goes
into the air. It is similar to carbonated soda
drinks where carbon dioxide is dissolved in the
soda and is released when you open the bottle.
Some radon also stays in the water.
Radon is not a concern in water that comes
from lakes, rivers, and reservoirs (called
surface water), because the radon is released
into the air before it ever arrives at your tap.
Why is radon in drinking water a
health concern?
Breathing radon in indoor air can cause lung
cancer. Radon gas decays into radioactive
particles that can get trapped in your lungs
when you breathe it. As they break down
further, these particles release small bursts of
energy. This can damage lung tissue and
increase your chances of developing lung
cancer over the course of your lifetime. People
who smoke have an even greater risk. Not
everyone exposed to high levels of radon will
develop lung cancer. However, radon in indoor
air is the second leading cause of lung cancer.
About 20,000 deaths a year in the U.S. are
caused by breathing radon in indoor air.
Only about 1-2 percent of radon in the air
comes from drinking water. However
breathing radon released to air from tap water
increases the risk of lung cancer over the
course of your lifetime. Some radon stays in
the water; drinking water containing radon also
presents a risk of developing internal organ
cancers, primarily stomach cancer. However
this risk is smaller than the risk of developing
lung cancer from radon released to air from tap
water.
Based on a National Academy of Science
report, EPA estimates that radon in drinking
water causes about 168 cancer deaths per
year: 89% from lung cancer caused by
breathing radon released to the indoor air from
water and 11 % from stomach cancer caused
by consuming water containing radon.
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Is there radon in my water?
Not all drinking water contains radon. If your
drinking water comes from a surface water
source, such as a river, lake, or reservoir, most
radon that might be in the water will be
released into the air before reaching your water
supplier or home. Radon is only a concern if
your drinking water comes from underground,
such as a well that pumps water from an
aquifer, though not all water from underground
sources contains radon.
If you get your water from a public water
system that serves 25 or more year-around
residents, you will receive an annual water
quality report. A major public right-to-know
initiative of the 1996 Amendments to the Safe
Drinking Water Act, these water quality reports
will tell you what is in your water (including
radon if it has been tested), where it comes
from, and how to help protect it.
What levels of radon in indoor air
should I be concerned about?
There is no federal regulation for radon in
indoor air. However, EPA does recommend
that you take action to reduce your home's
indoor radon levels if you test your home and
find levels at or above 4 pCi/L (picoCuries per
liter, a unit of measurement for radiation). EPA
and the U.S. Surgeon General recommend that
everyone test their homes (and apartments
located below the third floor). In most homes,
radon levels can be reduced to 2 pCi/L or less.
In addition, new homes should be built radon
resistant, especially in high radon areas.
For more information about how to test the air
in your home for radon and fix the problem,
contact the Radon Hotline at 1-800-SOS-
RADON. If you think the radon in your indoor
air comes from the water, see "How do I test
for radon and how do I get rid of it?"
What levels of radon in water
should I be concerned about?
There is currently no federally-enforced
drinking water standard for radon. EPA is
proposing to regulate radon in drinking water
from community water suppliers (water
systems that serve 25 or more year-round
residents). EPA does not regulate private
wells. EPA proposed the rule in October, 1999
and plans to finalize it in August, 2000.
EPA is proposing to require community water
suppliers to provide water with radon levels no
higher than 4,000 pCi/L, which contributes
about 0.4 pCi/L of radon to the air in your
home. This requirement assumes that the
State is also taking action to reduce radon
levels in indoor air by developing EPA-
approved, enhanced State radon in indoor air
programs (called Multimedia Mitigation
Programs). This is because most of the radon
you breathe comes from soil under the house.
This option gives States the flexibility to focus
on the greatest problems, by encouraging the
public to fix radon in indoor air problems and
build homes that keep radon from entering.
For States that choose not to develop
enhanced indoor air programs, community
water systems in that State will be required to
reduce radon levels in drinking water to 300
pCi/L. This amount of radon in water
contributes about 0.03 pCi/L of radon to the air
in your home. Even if a State does not
develop an enhanced indoorair program, water
systems may choose to develop their own local
indoor radon program and meet a radon
standard for drinking water of 4,000 pCi/L.
EPA has set up this option, under the
framework specified by the 1996 Amendments
to the Safe Drinking Water Act, so that the
overall risks from exposure to radon, both
through air and water, are reduced.
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How do I test for radon and how
do I get rid of it?
Because radon in indoor air is the larger health
concern, EPA recommends that you first test
the air in your home for radon before testing for
radon in your drinking water. EPA and the
U.S. Surgeon General recommend testing all
homes for radon in indoor air (and apartments
located below the third floor). EPA
recommends that you take action to reduce
your home's indoor radon levels if your radon
test result is 4 pCi/L or higher.
If you have tested the air in your home and
found a radon problem, you may also want to
find out whether your water is a concern:
• If you get water from a public water
system: Find out whether your water
system gets its water from a surface (river,
lake, or reservoir) or a ground water
(underground) source.
> If the water comes from a surface water
source, most radon that may be in the
water will be released to the air before it
makes its way to your tap.
> If the water comes from a ground water
source, call your water system and ask if
they've tested the water for radon.
If you have a private well: EPA
recommends testing your drinking water for
radon. Call the Safe Drinking Water
Hotline (1-800-426-4791) which can provide
phone numbers for your State laboratory
certification office or call the Radon Hotline
(1-800-SOS-RADON) which can provide
phone numbers for your State radon office.
Your State laboratory certification office or
State radon office can direct you to
laboratories which may be able to test your
drinking water for radon.
If testing your private well shows that you have
high levels of radon in your drinking water and
you are concerned about it, there are some
things you can do to improve the water. The
most effective treatment you can apply is to
remove radon from the water right before it
enters your home. This is called point-of-entry
treatment. There are two types of point-
of-entry devices that remove radon from water:
• Granular activated carbon (GAC) filters
(which use activated carbon to remove the
radon), and
• Aeration devices (which bubble air through
the water and carry radon gas out into the
atmosphere through an exhaust fan).
GAC filters tend to cost less than aeration
devices, however, radioactivity collects on the
filter, which may cause a handling hazard and
require special disposal methods for the filter.
For more information on aerators and GAC
filters, you should contact two independent,
non-profit organizations: NSF International at
(800) 673-8010 and the Water Quality
Association at (630) 505-0160.
I receive water from a public
water supplier. How will EPA's
proposed regulation affect me?
Your State may decide to develop a plan for an
enhanced radon in indoor air program, which
would require your public water supplier to
reduce radon levels in the water supply to
4,000 pCi/L. Consumers may be interested in
participating in theirState's development of this
plan, once the radon rule is finalized (expected
in August, 2000). If your State or public
supplier does not develop an enhanced radon
in indoor air program, your public water
supplier is required to reduce radon levels to
300pCi/L. Under either option, your water bills
may increase depending on the size of your
water supplier and the radon levels in the
drinking water in your area.
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How do I get more information
about radon?
Call the Safe Drinking Water Hotline
(1-800-426-4791):
The Safe Drinking Water Hotline can provide
you with more information about what EPA is
doing to regulate radon in drinking water and
refer you to your State drinking water program
for information about your community water
system. Or, visit EPA's web site on drinking
water at http://www.epa.gov/safewater for more
information.
Call your Local Water Supplier:
Your local water supplier will have information
about your local water supply and can answer
any questions you have about your water.
Look for the phone number on your water bill
or in the government section of your phone
book.
Call the Radon Hotline (1-800-SOS-RADON):
The Radon Hotline can refer you to your State
radon office for more information, and can
send you free publications about radon in
indoor air, including: "A Citizen's Guide to
Radon," "The Home Buyer's and Seller's Guide
to Radon," and the "Consumer's Guide to
Radon," which provide information on how you
can test for radon levels in your indoor air and
how indoor air radon problems can be fixed.
Or, visit EPA's web site on radon at
http://www.epa.gov/iaq/radon for more
information
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