Effects of Arsenic In Water and How To Treat It

Arsenic in water supplies is rarely found at toxic levels. However, it is a dangerous contaminant that should be addressed when discovered.

While arsenic is often portrayed as a method of poisoning in films and television, it occurs naturally in many areas. Wells drilled into certain bedrock frequently contain arsenic at some level.

What happens when the levels get too high? How is arsenic removed from the water supply? Here we will examine the answers to these important questions.

The Health Impacts of Arsenic

Arsenic is known to cause a diverse range of health problems when ingested. Of course, the problems and severity of them depend on many factors including how much is present in the water supply and each individual’s sensitivity to it.

Long Term Health Impacts

Short Term Health Impacts

Skin, Bladder and Lung Cancer Risk


Skin Discoloration


Thickening of Skin


Growths on Extremities

Numbness in Extremities

As you can see, the impacts from exposure to arsenic can be severe. Needless to say, avoiding or removing arsenic from the water supply is of the utmost importance.

The Standards for Arsenic Levels

The standards set forth by the United States Environmental Protection Agency say that only .010 parts per million (ppm), or 10 parts per billion (ppb), is safe. Originally, the recommendation was 50 ppb (.050 ppm) but the research suggested this contaminant level put people at an increased risk of bladder and kidney cancers.

Arsenic In Water

Those who discover arsenic over 10 ppb should consider their options for filtration systems and temporarily suspend consuming the water until the system is applied. Chronic consumption at even a little over 10 ppb could result in any number of health issues.

If tests show arsenic levels over 200 ppb, immediately discontinue drinking the water until a filtration system is installed. Showering, bathing, or cleaning is acceptable for levels up to 500 ppb but should not be a long-term situation.

The Remedies for Arsenic in the Water Supply

Find a certified laboratory to have your water supply tested for arsenic. If the results come back with levels higher than 10 ppb, it is time to consider options for removal.

There are many treatment methods available for removing arsenic from your water supply. Determining which method is appropriate depends on multiple influential factors.

Factors Impacting the Removal Method Decision

There are two different types, or species, of arsenic that occur naturally. Arsenic 3 represents the greatest challenge for removal, as it requires oxidation to the other species - Arsenic 5. The most popular oxidant is chlorine for home water supply treatment. 

Homeowners must also decide where to put the treatment system. Two options exist including point-of-use and point-of-entry. Point-of-use installs a filter at the tap and point-of-entry ensures the entire water system is treated.

If test results show high levels of iron or manganese in addition to arsenic, a system that removes them prior to treating the arsenic issue will be required.

Arsenic Removal Methods

After considering the factors that impact which methods are feasible, the choice comes down to weighing which system seems most beneficial to your setting and preferences. Each method has pros and cons that could impact the final choice.

Treatment System



Anion Exchange

Require Little Maintenance

Whole House Treatment

Higher Costs

Offers Point-of-Use

Lower Installation and Yearly Costs

Does Not Impact Arsenic 3

Requires Pre-Filtration

Activated Alumina

Easy to Discard

Anion Exchange

High levels of Arsenic 3 will often require the installation of a pre-oxidation system ahead of the filtration systems listed above. As most filtration methods are ineffective or inefficient at the removal of Arsenic 3, oxidation is a necessary step to guarantee safety. This can raise the cost of a treatment system significantly.

Arsenic - A Rare but Real Problem

A water supply featuring unsafe levels of arsenic is rare. However, if it does occur it can present significant health risks for anyone consuming it. Fortunately, there are treatment options available with a combination of oxidation (in the cases of Arsenic 3) and home filtration.