Lead in Drinking Water

Lead is a naturally occurring element that is present in some minerals in rocks and soils, but the main source of lead in drinking water is generally through contact with plumbing components containing lead. The amount of lead dissolved into drinking water depends on a number of factors including the pH, alkalinity and hardness of the water, as well as the length of time the water is in contact with lead bearing materials. Changes to regulations controlling plumbing components have greatly reduced the potential exposure to lead in drinking water.

What are the health concerns?

The principle concerns relating to elevated lead levels in drinking water are effects on the brain and nervous system, with potential for behavioural problems, learning disabilities and delayed development. To minimize these risks, the Guidelines for Canadian Drinking Water Quality, published by Health Canada, recommend that lead concentrations in drinking water should not exceed 0.005 mg/L. 

Because the drinking water guideline for lead is based long term  exposure, it is intended to apply to average concentrations in water consumed for extended periods and short-term consumption of water containing lead at concentrations above the guideline does not necessarily pose undue risk to health. In order to minimize exposure to lead introduced into drinking water from plumbing systems, it is also recommended that only the cold water supply be used, after an appropriate period of flushing to rid the system of standing water, for drinking, beverage preparation and cooking. The use of water with elevated levels of lead for other domestic uses such as bathing and laundry pose little risk and are considered acceptable.

What are the treatment options?

If sampling of your water indicates that lead concentrations are above the guideline value of 0.005 mg/L you should re-sample the water to confirm the initial results, taking care to ensure that the water is thoroughly flushed before collecting the sample. If the results of this second sample still show elevated lead levels you may want to have a plumber inspect your household plumbing to see if there are any older pipes or fixtures that could be the source of the lead. If no likely sources of lead can be identified, then you may wish to install a treatment device to remove the lead. Lead run 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, cation exchange or 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 44 for Cation Exchange Water Softeners, Drinking Water, 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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