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Arsenic and Drinking Water

What regulations address arsenic in drinking water. Removal requirements to meet MCLs, public notice requirements, and health effects of arsenic in drinking water.

Arsenic is a naturally occurring metal that is found in ground water in various parts of Texas. The highest levels of arsenic in Texas occur in the Ogallala and Gulf Coast aquifers. The MCL for arsenic is 0.010 milligrams per liter (mg/L) or 10 parts per billion (ppb).

Compliance Calculations

Compliance with the MCL is determined based on a running annual average of quarterly sampling at each point where treated water enters the distribution system.

Compliance Options

Systems that exceed the MCL are required to identify options to reduce the arsenic levels in their treated water. There are many methods available to minimize the amount of arsenic in drinking water. Systems can obtain new sources of water, or blend existing sources with alternate source with lower levels. Treatment processes include precipitation, adsorption, ion exchange, membrane filtration, and other alternative methods.

Health Effects

The EPA has determined that some people who drink water containing arsenic in excess of the MCL over many years could experience skin damage or problems with their circulatory system, and may have an increased risk of getting cancer. A MCL exceedance for arsenic is not an emergency.

Public Information

Your public water system will provide you with a notification during any quarter that the system exceeds the MCL. Additionally, the annual water quality report (Consumer Confidence Report) that a community water system prepares and distributes to its customers by July 1 of each year must report the minimum, maximum, and average level of arsenic in your drinking water if it is detected.