Municipally supplied drinking water contains very little lead, however, lead can leach into drinking water in older homes from their own pipes and service connections and plumbing solder.
In April 2007, elevated lead was found in tap water in a number of London, Ontario homes. The Chief Drinking Water Inspector ordered 36 municipalities to test for lead in older homes that were serviced by lead lines. This was followed by a provincial Lead Action Plan, which requires municipalities to test lead in their drinking water systems and take corrective action.
What is lead?
Lead is a toxic metal that was used for many years in products found in and around homes. Even at low levels, lead may cause a range of health effects including behavioral problems and learning disabilities. Children six years old and under are most at risk because this is when the brain is developing. The primary source of lead exposure for most children is lead-based paint in older homes. Lead in drinking water can add to that exposure.
How does lead get into tap water?
Typically, lead gets into your water after the water leaves your local treatment plant or your well. That is, the source of lead in your home's water is most likely from pipes or solder in your home's own plumbing. Older homes, particularly those constructed before 1955, often contain lead water service lines. Homes constructed prior to the mid to late 1980's may have their plumbing connected with lead base solder. For lengthy periods (over six hours), lead can dissolve into drinking water that is left standing in household piping made with these materials. The most common cause is corrosion, a reaction between the water and the lead pipes or solder. Dissolved oxygen, low pH (acidity) and low mineral content in water are common causes of corrosion. All kinds of water, however, may have high levels of lead.
What are the health effects of lead?
The health effects of lead are most severe for infants, children under six years of age, pregnant women and nursing mothers. For infants and children, exposure to high levels of lead in drinking water can result in delays in physical or mental development. For adults, it can result in kidney problems or high blood pressure. Although the main sources of exposure to lead are ingesting paint chips and inhaling dust, studies have shown that 10 to 20 percent of human exposure to lead may come from lead in drinking water. Infants who consume mostly mixed formula can receive 40 to 60 percent of their exposure to lead from drinking water. Health Canada has established a maximum acceptable concentration for lead in drinking water of 10 ppb (parts per billion) in a free flowing sample of water.
Flowing water samples better reflect the overall quality of household drinking water, and are indicative of normal lead exposure from drinking water. This drinking water guideline has been developed to protect the population most at risk, namely infants and young children.
What can I do to reduce the risk of exposure to lead?
- Always use cold, fresh water for drinking, cooking, making baby formula and preparing beverages.
- Do not drink water that has been standing in your household water pipes for more than six hours. To rid your plumbing system of standing water, let the water run for approximately one minute or until it feels cold to the touch. You can also use the flushed water for other purposes such as plant watering or household cleaning.
- Flushing the toilet and washing your hands, or taking a shower is more than sufficient to flush standing water from your pipes each morning.
- Do not use ceramic cookware from foreign countries to heat water or store food unless you're sure that they are lead-free.
- Do not store beverages in lead crystal containers.
- If you work around lead, shower and change clothing and shoes at work, and wash work clothes separately.
- Be aware that some hobby activities like furniture refinishing, model building and working with metals or stained glass can be sources of lead.
- Exterior paints should not be used indoors since they may contain lead.
Who do I call if I have questions or concerns about water quality?
Information on water quality may be obtained by calling your local municipality. You can also visit Health Canada's web site for more information on lead and human health.