Arsenic and Your Well Water: Part 3 of 3



Last post we discussed the potential health effects of arsenic exposure. This week, we will focus on how to treat an arsenic problem in your water.

Once your arsenic levels are tested, the degree of the cleanup job must be assessed.

How can you reduce high levels of arsenic in water?

If the arsenic level in your water is at or above 10 µg/L, refrain from consumption such as drinking or cooking.

There are two strategies to remove a contaminant from the water you use:

  • Point-of-Entry (POE) treatment systems will treat the water for your entire household
  • Point-of-Use (POU) systems will treat the water as it comes out of your tap

Reverse Osmosis (RO) systems can be effective for arsenic removal. RO systems run water through a filter specifically sized to pass water molecules and trap larger molecules such as iron and arsenic. RO is most effective as a Point-of-Use system, typically at the kitchen sink. A larger RO can be used also as a Point-of-Entry treatment for the whole houses’ water supply. Though these often can cause corrosion issues in the plumping which can lead to other water quality problems, such as increased concentrations of lead or copper.

The preferred treatment technology is an Iron Oxide Absorption system. This particular system works effectively to remove arsenic and it is both easy to maintain and operate.


The granular media inside the filter has a large surface area of material that has an affinity to bond to arsenic. Arsenic is then effectively absorbed out of the water. Filter cartridges can be POE or POU depending on their size. The media must however, be replaced on a regular basis.

Other methods such as anion exchange are also effective. In order to choose the best treatment system, household owners should consult their local health officers or certified water specialists before deciding which system to use as the water chemistry, geology, and water use are important considerations in the treatment.

A word of caution, in attempting to remove arsenic from your water, do not boil it. Boiling will just increase the concentration of arsenic in the water. The contaminant will stay behind as the water boils off, resulting in a higher concentration of arsenic at the end than you started with.


If a system is installed in your home, make sure to get your water tested again post-treatment. This is an important step to ensure your system is working properly, set to the correct settings, and restoring the quality of your water.

About the Author Gerry Bulfin

Need help with your well water? I have been assisting homeowners, small communities and businesses improve their well water quality since 1989. Please email me at if you have a question about water testing, test kits or well water systems in general. Gerry Bulfin CWS-IV Master Water Specialist WQA Certified Licensed California Water Treatment Contractor