Chemical Rule

Inorganic Contaminants

Inorganic Contaminants (IOCs) are elements or compounds found in water systems and may be natural in the geology or caused by activities of man through mining, industry or agriculture. It is common to have trace amounts of many Inorganic Contaminants in water systems. Amounts above the Maximum Contaminant Level (MCL) may cause a variety of damaging effects to the liver, kidney, nervous system, circulatory system, blood, gastrointestinal system, bones, or skin depending upon the inorganic contaminant and level of exposure. Some Inorganic Contaminants are more damaging to infants and pregnant women. Because of some special aspects of the rules for arsenic, fluoride, and nitrates, separate pages can be found on this web site.

All community and non-transient non-community public water systems must monitor for regulated IOCs. At the present there are 15 regulated Inorganic Contaminants (including fluoride, arsenic, and nitrates).

  • Monitoring

    All community and non-transient non-community public water systems must monitor for regulated IOCs. At the present there are 15 regulated Inorganic Contaminants (including fluoride, arsenic, and nitrates).

Synthetic Organic Contaminants

Synthetic Organic Contaminants (SOCs) are man-made compounds used for a variety of industrial and agricultural purposes. This group of contaminants includes pesticides, PCBs, and dioxin. SOC health effects include damage to the nervous system, kidneys and cancer risks.

  • Monitoring

    Both community and non-transient non-community public water systems must monitor for these organic contaminants. Transient water systems do not have to test for these chemicals.

Volatile Organic Contaminants

Volatile Organic Contaminants (VOCs) are man-made compounds used for a variety of industrial and manufacturing purposes. VOCs are not readily dissolved in water and will tend to separate from the water forming gasses. VOCs have various effects on the liver, kidneys, nervous system and some pose a cancer risk.

  • Monitoring

    Community and non-transient non-community public water systems must test for these contaminants. Transient non-community water systems such as campgrounds are not required to test for VOC’s in their water supply.

Maintaining Compliance

Compliance is achieved by monitoring quarterly, annually or one sample every three years. If a sample exceeds the MCL, quarterly monitoring is triggered for four quarters. If the running annual average for four quarters is reliably and consistently below the MCL, the system will qualify for reduced monitoring.

Chemical Waivers

The United States Environmental Protection Agency (EPA) has authorized states to issue reduced monitoring waivers for inorganic and organic chemicals to PWSs that have completed an approved waiver application and review process. The Montana Department of Environmental Quality (DEQ) allows decreased monitoring of specific inorganics (IOC and asbestos) and organic (SOC and VOC) chemicals. For more information regarding Chemical Waivers please visit the Chemical Waiver Rule page.

Contact

Diane Jordan
Chemical/Radiological/ Waiver Rule Manager
PO Box 200901
Helena, MT 59620
Phone: (406) 444-6741
Fax: (406) 444-1374
DEQ: (406) 444-4400

Resources

https://www.epa.gov/