Testing for Radon in Water
One may care about radon in water not because of the direct
effects, but because of off-gassing that may occur when the water is
agitated or aerated such as during laundry, dishwashing or
showering. The rule of thumb is that 10,000 picoCuries per liter (pCi/l)
of water translates into about 1 pCI/l average concentration in air.
The EPA Citizen's Guide to Radon flatly recommends
testing water whenever both these conditions are met:
- The house is supplied by well water, and
- The radon concentration (in air) is 4 picoCuries per liter
or more.
We would be happy to conduct such a test for you.
It's interesting to watch the intramural battle at EPA between
the indoor air and drinking water factions. The issue is acceptable
risk. Water regulations have traditionally been set to achieve at
most 1 in 100,000 lifetime fatality risk, leading to a standard on
the order of 300 picoCuries per liter of water (roughly equivalent
to 0.03 pCi/l in air, or less than 10% of typical fresh air radon
content). The indoor air people say this is, well, silly.
Radon in Water
The radon in your home's indoor air can come from two sources,
the soil or your water supply. Compared to radon entering your
home through water, radon entering your home through soil is a much
larger risk. If you've tested for radon in air and have
elevated radon levels and your water comes from a private well, have
your water tested. The devices and procedures for testing your
home's water supply are different from those used for measuring
radon in air.
The radon in your water supply poses an inhalation risk and an
ingestion risk. Research has shown that your risk of lung
cancer from breathing radon in air is much larger than your risk of
stomach cancer from swallowing water with radon in it. Most of
your risk from radon in water comes from radon released into the air
when water is used for showering and other household purposes.
Radon in your home's water in not usually a problem when its
source is surface water. A radon in water problem is more
likely when its source is ground water, e.g., a private well or a
public water supply system that uses ground water. Some public
water systems treat their water to reduce radon levels before it is
delivered to your home. If you are concerned that radon may be
entering your home through the water and your water comes from a
public water supply, contact your water supplier.
If
you've tested your private well and have a radon in water problem,
it can be fixed. Your home's water supply can be treated in one of
two ways. Point-of-entry treatment can effectively remove
radon from the water before it enters your home.
Point-of-entry treatment usually employs either granular activated
carbon (GAC) filters or aeration devices. While GAC filters
usually cost less than aeration devices, filters can collect
radioactivity and may require a special method of disposal.
Point-of-use treatment devices remove radon from your water at the
tap, but only treat a small portion of the water you use, e.g., the
water you drink. Point-of-use devices are not effective in
reducing the risk from breathing radon released into the air from
all water used in the home.
For information on radon in water, testing and treatment, and
existing or planned radon in drinking water standards, or for
general help, call EPA's Drinking Water Hotline at (800) 426-4791 or
visit
www.epa.gov/safewater/radon.html. If your water comes from
a private well, you can also contact your state radon office.
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.
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 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 indoor air
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.
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 (877) 867-3435 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 their State'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 300 pCi/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.