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Arsenic facts – Watts PWRO4 User Manual

Page 12

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Arsenic Facts

Arsenic (As) is a naturally occurring contaminant found in many

ground waters . Arsenic in water has no color, taste or odor . It must

be measured by an arsenic test kit or lab test .
Public water utilities must have their water tested for arsenic . You

can obtain the results from your water utility contained with in your

consumer confidence report . If you have your own well, you will need

to have the water evaluated . The local health department or the state

environmental health agency can provide a list of test kits or certified

labs .
There are two forms of arsenic: pentavalent arsenic (also called As

(V), As (+5)) and trivalent arsenic (also called As (III), As (+3)) . In well

water, arsenic may be pentavalent, trivalent, or a combination of

both . Although both forms of arsenic are potentially hazardous to

your health, trivalent arsenic is considered more harmful than pen-

tavalent arsenic .
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 potas-

sium permanganate will also change trivalent arsenic to pentavalent

arsenic . A combined chlorine residual (also called chloramine) where

it does convert trivalent arsenic to pentavalent arsenic, may not con-

vert all the trivalent arsenic in to pentavalent 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 .
This Watts reverse osmosis system is designed to remove up to

98% of pentavalent arsenic . It will not convert trivalent arsenic to

pentavalent arsenic . Under laboratory standard testing conditions,

this system reduced 0 .30 mg/L (ppm) pentavalent arsenic to under

0 .010 mg/L (ppm) . (The USEPA standard for drinking water) . Actual

performance of the system may vary depending on specific water

quality conditions at the consumer’s installation . In addition to the

independent laboratory standard testing conditions, Watts has

conducted additional field testing on our reverse osmosis units to

determine trivalent arsenic reduction capabilities . Based upon Watts

field testing, it has been determined that the RO units are capable of

reducing up to 67% of trivalent arsenic from the drinking water .
The RO membrane component of this Watts reverse osmosis system

must be maintained according to its recommended maintenance

cycle . Specific component identification and ordering information can

be found in the installation/operation manual maintenance section,

by phone at 1-800-224-1299 or online www .watts .com