United States
Environmental Protection
Agency
Office of Water
(4607)
EPA815-F-99-007
October 1999
                RADON IN DRINKING WATER:
                Questions and Answers
                               FAOTSHEET
  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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