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9.1 Arsenic Facts
Arsenic (abbreviated As) is found naturally in some well water. Arsenic in water
has no color, taste, or odor. It must be measured by a laboratory test. Public
water utilities must have their water tested for arsenic. You can get the results
from your water utility. If you have your own well, you can have the water
tested. The local health department or state environmental health agency
can provide a list of certified labs. The cost is typically $15 to $30. Information
about arsenic in water can be found on the internet at the U.S. Environmental
Protection Agency website:
www.epa.gov/safewater/arsenic.html.
There are two forms of arsenic: pentavalent arsenic (also called As(V), As(+5),
and arsenate) and trivalent arsenic (also called AS(III), As(+3), and arsenite).
In well water, arsenic may be pentavalent, trivalent, or a combination of both.
Special sampling procedures are needed for a lab to determine what type
and how much of each type of arsenic is in the water. Check with the labs in
your area to see if they can provide this type of service.
Reverse osmosis (RO) water treatment systems do not remove trivalent arsenic
from water very well. RO systems are very effective at removing pentavalent
arsenic. A free chlorine residual will rapidly convert trivalent arsenic to
pentavalent arsenic. Other water treatment chemicals such as ozone and
potassium permanganate will also change trivalent arsenic to pentavalent
arsenic. A combined chlorine residual (also called chloramine) may not
convert all the trivalent arsenic. If you get your water from a public water utility,
contact the utility to find out if free chlorine or combined chlorine is used in
the water system.
The
HydroSplash
systems are designed to remove pentavalent arsenic. They
will not convert trivalent arsenic to pentavalent arsenic. The system was tested
in a lab. Under testing conditions, the systems
typically
reduced 0.30 mg/L
(ppm) pentavalent arsenic to 0.010 mg/L (ppm) (the USEPA standard for
drinking water) or less. The performance of the system may be different at
your installation. Have the water tested for arsenic to check whether the
system is working properly.
The RO component in these systems must be replaced every 12 months or
when the test above rises above 10ppm to ensure the system will continue
to remove pentavalent arsenic. The component identification and locations
where you can purchase the component are listed in the installation/operation
manual.
