Arsenic Fact Sheet - Pentair FRESHPOINT GRO-475M Installation And Operation Manual

Arsenic Fact Sheet

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 lab 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.
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 GRO-475B/GRO-475M system is designed to remove
pentavalent arsenic. It will not convert trivalent arsenic to
pentavalent arsenic. The system was tested in a lab. Under
those conditions, the system reduced 0.050 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 treated water
tested for arsenic to check if the system is working properly.
The RO component of the GRO-475B/GRO-475M system
must be replaced every 12-24 months 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.
18 • FRESHPOINT GRO-475B/GRO-475M Installation and Operation Manual