Arsenic is present in water due to leaching from natural deposits and human activities such as petroleum production, spraying of pesticides and commercial semiconductor manufacturing processes.
In water, Arsenic exists in 2 forms
- Pentavalent Arsenic, which is also called AS(V), As+5, and Arsenate
- Trivalent Arsenic, which is also called AS(III), As+3, and Arsenite
The US Environmental Protection Agency (EPA) maximum contamination level goal for arsenic is ZERO. However, since with best available technology this is not feasible (taking cost into consideration), the EPA enforces a maximum contaminant level of 0.010 mg/L (or ppm) in public water systems. World Health Organization guideline for maximum arsenic concentration in drinking water also remains at 10 parts per billion.
Potential health effects from Arsenic may include cancer (skin, bladder, lung, kidney, liver, prostrate), skin problems & cardiovascular/nervous system problems.
Always contact a water treatment system manufacturer before purchasing a filter to treat arsenic issues. pH, amount of oxygen in water, iron, can all affect performance.
In arsenic contaminated water where the concentration exceeds 10 ppb, regardless of what you install for the whole house, it is highly recommended to install a reverse osmosis (RO) drinking water system certified under ANSI/NSF standard 58 for redundant protection, which covers arsenic reduction as well as filterable cyst reduction, lead reduction, total trihalomethane (TTHM) reduction & volatile organic chemical (VOC) reduction. Make sure your home water distribution system has 65 psi or more line pressure for the drinking water RO or buy a certified system with a booster pump. Keep in mind that RO is only effective against the pentavalant form of Arsenic. Trivalent form of Arsenic, if exists in your water, must be oxidized to pentavalent form before it can be treated by an RO. Whole house chlorine pumps followed by contact tanks, ozone treatment and potassium permanganate are popular oxidizing treatments that can convert trivalent arsenic into pentavalent form that can be easily treated by reverse osmosis purification.
A drinking water distillation system certified under ANSI/NSF 62 would also be very effective against arsenic as well.
Contact a water filter manufacturer direct for a solution rather than purchasing an off the shelf product if your arsenic concentration exceeds 30 ppb. In this case you will need multiple treatment equipment to deal with the toxic levels of arsenic and a certified RO alone will not be enough.
Current treatment methods for arsenic include oxidation and filtration (eg. chlorination followed by activated carbon), activated alumina, nano titanium oxide, distillation, strong base anion exchange resins (commercial only), manganese greensand and reverse osmosis.