Division of Environmental and Community Health

Maine Center for Disease Control & Prevention

A Division of the Maine Department of Health and Human Services

DHHSMeCDCEnvironmental and Community HealthDrinking WaterDrinking Water Consumers Arsenic


What is Arsenic?

Arsenic is a semi-metal element in the periodic table. It is odorless and tasteless. It enters drinking water supplies from natural deposits in the earth or from agricultural and industrial practices.

What is the Maximum Contaminant Level (MCL) for Arsenic?

The Environmental Protection Agency (EPA) has established a standard for arsenic in drinking water at 10 ppb (micrograms per liter, µg/L).

What are the Health Effects of Arsenic?

Non-cancer effects can include thickening and discoloration of the skin, stomach pain, nausea, vomiting; diarrhea; numbness in hands and feet; partial paralysis; and blindness. Arsenic has been linked to cancer of the bladder, lungs, skin, kidney, nasal passages, liver, and prostate.

What are the Best Available Treatment Technologies for Arsenic?

EPA identifies the following treatment technologies as Best Available Technologies for removing Arsenic from drinking water:

  • Anionic Exchange
  • Reverse Osmosis
  • Iron Oxide Filters
  • Activated Alumina
  • Modified Coagulation/Filtration
  • Modified Lime Softening
  • Electrodialysis Reversal

The Drinking Water Program recommends that water systems and home howners seek advice from a water treatment professional to determine the most effective treatment based on the characteristics of their specific water system. Public water systems should contact the Drinking Water Program for approval before installing or making changes to any treatment in their system.

Arsenic Treatment Checklist:

  • Have I had my water tested at a state certified laboratory?
  • Have I done a retest to confirm the results?
  • Have I also tested for iron and manganese? They are very common in Maine and can foul RO systems. They may also require removal.
  • Have I contacted a water treatment professional to aid in the analysis and the selection of an adequate solution?
  • Do I need whole house treatment or is point of use treatment adequate?
  • Have I checked references (other homes that he/she has worked in) for the water treatment professional I've selected?
  • Are there other problems with my drinking water system that should also be addressed?

Additional Resources