Maximum Contaminant Level



California MCL – 0.006 mg/L or ppm

Massachusetts MCL – 0.002 mg/L

US EPA National MCL pending


US EPA – 0.015 mg/L

Arizona – 0.014 mg/L

New York – 0.005 mg/L

Maryland, New Mexico, New Hampshire – 0.001 mg/L

Action Level

New York – 0.018 mg/L

Nevada – 0.001 mg/L

Texas – 0.004 mg/L

Map of Perchlorate Detections1

Perchlorate is a naturally occurring element, however, it also exists as a man-made inorganic chemical. It is an oxidizer and is used in the manufacturing of fireworks, explosives, and other pyrotechnics. Water and soil contamination occur mostly in areas where the manufacture, use, and storage of munitions and rocket propellants took place throughout the last 50 years. Perchlorate can cause significant damage to the thyroid, which is responsible or producing essential hormones for growth and the regulation of metabolic processes. Extended exposure can lead to hypothyroidism, which causes chronic metabolic disorders and can cause abnormal fetal growth in pregnant women. It may also stunt the mental growth of infants and young children. Perchlorate is of particular concern for children under the age of two because of their body weight.

Perchlorate can be removed from drinking water by the following treatments:

  • Reverse Osmosis
  • Anion Exchange (Regenerable and non-regenerable)
  • Distillation

1. World Health Organization. Perchlorate Fact Sheet. [Online] 2013.