Arsenic in Drinking Water
Arsenic Rule at a Glance
Maximum Contaminant Level
in parts per million (ppm)
MCL = 0.010 ppm
Maximum Contaminant Level Goal MCLG = 0 ppm
Skin damage or problems with circulatory systems, and may have increased risk of getting cancer
Sources of contamination
Erosion of natural deposits; runoff from orchards, runoff from glass & electronic production wastes
For other contaminants and their MCLs, visit this page.
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.
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.
EPA has set the arsenic standard for drinking water at .010 parts per million (10 parts per billion) to protect consumers served by public water systems from the effects of long-term, chronic exposure to arsenic. Water systems must comply with this standard by January 23, 2006, providing additional protection to an estimated 13 million Americans.
This web site is designed to provide you with information about arsenic in drinking water and provide guidance materials to help the states and water systems comply with the standard.
- Basic Information – Learn more about the sources of arsenic, health effects and our frequently asked questions.
- Arsenic Rule – Get updated information on the arsenic rule, including quick reference guides. The history of the rule-making is also featured.
- Compliance Help – If you need to comply with the arsenic rule, visit this page to get available tools and training information.
- State Guidance – If you are with a state agency, visit this page to get available guidance information about arsenic implementation.
- Funding Sources – This page gives you the information you will need to seek funding to help you comply with the arsenic rule.
- Publications – Visit a list of all the publications offered by EPA on arsenic. Many are on-line for your use.
- Research – Find out about EPA’s research program on arsenic.