Arsenic in Drinking Water

Arsenic is a naturally occurring element that is widely distributed throughout the Earth’s rocks and soils. Arsenic can be dissolved from arsenic bearing minerals in the soil or rock and be present in groundwater. On a more local basis, arsenic can also be released into water through human activities. In most areas, food is the primary source of arsenic in our diets; however in some locations, with high levels of arsenic, drinking water may be the primary source.

What are the health concerns?

Arsenic is known to be a human carcinogen, and it is recommended concentrations in drinking water be kept as low as possible.  Consumption of drinking water with low levels of arsenic can increase the life time risk of certain types of cancer. To minimize this risk, the Guidelines for Canadian Drinking Water Quality, published by Health Canada, recommend that arsenic concentrations in drinking water should not exceed 0.01 mg/L. 

Short term consumption of water with much higher levels of arsenic can cause sickness including nausea, diarrhea and muscle pain, however it is highly unlikely that these concentrations would be present in groundwater or drinking water in Prince Edward Island. 

Precautions: The drinking water guideline for arsenic is based on life time exposure, and for short term exposure to drinking water moderately above the drinking water guideline of 0.01 mg/L the first step should be to follow-up by re-sampling the water supply to confirm the initial results. If the presence of arsenic at levels above the guideline are confirmed you can either treat the water to remove the arsenic, or choose an alternate, safe source of water for drinking and cooking. The use of water with elevated levels of arsenic for other domestic uses such as bathing and laundry pose little risk and are considered acceptable.

What are the treatment options?

Arsenic can be removed from drinking water by several treatment processes, and homeowners should consult with a reputable water treatment specialist to determine the best equipment for their homes. Some of the more common and effective methods of treatment include reverse osmosis, anion exchange and distillation. 

The Department does not recommend specific brands of treatment devices; however, it is recommended that consumers purchase devises bearing a label that indicates it has been certified to NSF/ANSI Standard 58 for Reverse Osmosis Drinking Water Treatment Systems or NSF/ANSI Standard 62 for Drinking Water Distillation Systems. 

As with the use of any drinking water treatment device, the effectiveness of treatment should be verified by sampling after installation. In addition, it is important to ensure the device is used and maintained according the manufacturer’s directions and its performance periodically confirmed by sampling.


Published date: 
February 5, 2024
Environment, Energy and Climate Action

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