World Water Day: Lead in Drinking Water

Megan Perez & Naomi Pitcher | March 2024

Lead in drinking water is one of the major contributors to lead exposure which can negatively impact human health. Studies have linked elevated blood lead levels to reduced cognition in children, and damage to nervous systems, kidneys and blood formation in both adults and children. The only way to know for sure if there is lead in potable water sources is to sample and analyse water for lead content.

Table of Contents

How does lead get into water?

Lead is often leached into water through lead-containing pipes that form part of the plumbing and distribution systems associated with municipal and private potable water supply. Lead could also be present in the pipe soldering materials used for joining pipes made of other metals (for example, copper).

If water has particularly low pH (high acidity), pipe corrosion occurs at a faster rate and can lead to higher lead levels (if lead-pipes are present along the distribution system).

Source: EPA Infographic: Lead in Drinking Water, August 2017, (original image edited)

What are the health effects of lead in water?

Research has shown that lead can impact the neurological health of susceptible individuals, especially children, pregnant women, and fetuses. On a biomolecular level, lead can inhibit or copy the functions of calcium in the body, therefore impacting bone health and development. Lead can bioaccumulate in the body over time, so long term exposure to lead will cause greater damage in the body. For children exposed to lead, studies have shown negative impacts on brain development. The presence of elevated levels of lead in the blood have been linked with:

  • Damaged kidneys,
  • Detrimental impacts on blood formation in body,
  • Damage to the central and peripheral nervous system (with possible results including lower IQ levels, learning disabilities and hearing loss in children),
  • Severe neurological and behavioural effects, particularly in children whose rapidly growing bodies can absorb lead more quickly.

What are the regulatory limits on lead in water?

Requirements for testing and the limits for lead in drinking water in Ontario is regulated by Ontario Regulation (O.Reg.) 169/03.   O.Reg. 169/03 contains the Ontario Drinking Water Quality Standards (DWQS), which was made under the Safe Drinking Water Act, 2002, S.O. 2002, c. 32.

ECOH compares the lead concentration in potable water to the O.Reg 169/03 standard of 10 micrograms per litre (µg/L).

Regulatory sampling requirements in Ontario

Under O.Reg. 170/03, the MECP instigated a community lead testing program, requiring municipalities to test for lead in water from a representative sampling of private residences, non-residential buildings and distribution sources (e.g., fire hydrants). Twice per year (in both winter and summer), samples are to be collected and analysed by accredited laboratories to determine the lead content in municipal water supplies.

Schools, day cares, and child care centres are required to register with the MECP under O.Reg 243/07. These facilities are required to have annual water sampling done, with results submitted to the MECP. Starting in December 2023, the MECP mandated that these registered facilities make public their lead water sampling results.

How do I know if there is lead in my water?

Lead in water is colourless, odourless and tasteless and cannot be detected by any means other than laboratory testing.

There are, however, indicators of lead in water that may include factors such as:

  • Historical knowledge of lead pipes used in the area. This information can be found on your local municipalities’ website. The older the pipes, the more likely they are to be lead-containing (whether in the pipe material or in solder on joints). However, this does not exclude newer pipes/joints from containing lead!
  • Water acidity. Water with a higher acidity level (pH less than 7) is more likely to corrode pipes and increase lead in water.

The only way to know for sure if your potable water contains lead is to perform sampling and testing.


Potable water sources include water fountains, faucets, kitchen sinks, water coolers and water purification systems. There are two samples collected during the testing of any potable (drinking) water source:

1.      Standing Water Testing

Standing water refers to water that has been standing within pipes for at least 6 hours. If testing of this standing water shows elevated lead concentrations, the exceedance is likely attributed to pipes within the distribution system containing lead.

2.      Flushed Water Testing

Once the standing water has been sampled, the water is run through the outlet for 5 minutes to flush the system. This removes any water that has been standing in the plumbing and is a way to ensure that testing is performed on water from the source. Sampling protocol for flushed water then requires that the sampler waits between 30 and 35 minutes. The waiting period allows for water to flow into the system from the source. If analysed flushed samples return with elevated lead levels, the lead exceedance is most likely linked to the water source.

If my property/facility is on well water, do I need to be concerned about lead levels?

Lead in water is possible wherever there are lead-containing distribution systems, including from well water. If a school, day care or child care centre is on well water, it remains a requirement under O.Reg. 243/07 to perform annual testing for lead in water.

If your facility is not a school or day-care centre, any potable water system linked to a well is recommended to be tested as part of a Health and Safety Due Diligence program (and under Section 5(a)(1) of the Occupational Safety and Health Act’s general duty clause requiring employers to keep workplaces free from any hazards likely to cause death or serious physical harm to employees).

ECOH has managed and performed potable lead-water sampling programs for clients across Canada. While not the topic of this blog, ECOH can also perform larger water sampling programs including:

  • Microbiology: total coliforms, e.coli
  • Turbidity
  • pH
  • Inorganics: hardness, chlorine levels, arsenic
  • And much more

Reach out to our team of experts if any of these are concerns at your facility or building:

Talk to an Expert

If standing water has high lead levels

If flushed water has high lead levels

  • Water in the system should be thoroughly flushed by running water for 10 minutes daily before use.
  • Confirmatory sampling is required following the flush to determine that lead levels have been reduced by flushing.
  • If flushing of standing water does not reduce lead levels, recommendations include the replacement of piping systems.
  • Install a National Sanitation Foundation (NSF) approved filter specifically designed to remove lead in water.
  • Follow installation of filter with confirmatory sampling to determine filter’s effectiveness.
  • If the filter is not reducing lead levels, recommendations include the replacement of piping systems.
*Note that lead in water cannot be removed through boiling

If schools, day cares and child care centre sampling programs reveal lead exceedances, the MECP requires that notification is made to:

  • The Spills Action Centre
  • The local Public Health Unit, and
  • The Ministry of Education

And that notification is made to these agencies within 24 hours of receipt of results. These agencies monitor the implementation of remediation efforts through communication with the environmental consultant who ensures that all regulatory requirements are followed to protect both children and adults from lead in water.

Talk to our Lead Testing Experts

Since 2003, ECOH has performed thousands of lead in potable water investigations. Our experienced team has managed cross-Canada sampling programs for federal properties and all over Ontario for school boards, day care centres and child care facilities, as well as municipalities and private businesses.

ECOH prides itself on timely and effective communication with regulatory bodies and health agencies, acting as a liaison between school safety officials and the regulators.

Reach out to us today for an obligation-free chat about how we can help you keep your people safe from lead in drinking water.

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  1. Penn State Extension. (2022, August 26). Lead in Drinking Water.,water%20at%2015%20%C2%B 5g%2FL
  2. ‌US EPA,OW. (2016, February 2). Basic Information about Lead in Drinking Water | US EPA. US EPA.
  3. Health Canada. (2007, July 24). Water Talk – Lead in drinking water.

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