Lead contamination in drinking water occurs when the element enters the water supply, often from plumbing materials. While lead is rarely found in the water source itself, it can dissolve into tap water as it travels through pipes and fixtures. Lead can be filtered out of water using various treatment methods. Understanding how lead gets into water and the technologies available for its removal can help ensure safer drinking water.
How Lead Enters Drinking Water
Lead typically enters drinking water through the corrosion of plumbing materials within a home or service line, rather than being present in the water source itself. This corrosion, a chemical reaction between water and lead-containing metals, is more pronounced when water has high acidity or low mineral content. Lead service lines, connecting a home to the public water main, are common points of entry, especially in older cities and homes built before 1986.
Beyond service lines, household plumbing also contributes to lead contamination. Lead solder, used to join copper pipes before 1987, is a significant source. Newer brass faucets and fixtures can leach lead into water, especially when water sits in them for several hours. Galvanized iron pipes, installed before the 1960s, can also attract and release lead particles if a lead service pipe was present.
When water remains stagnant in pipes or fixtures for extended periods, such as overnight, it has more time to dissolve lead. This can lead to higher lead concentrations in the first draw of water. Disturbing lead pipes, such as during plumbing repairs, can also temporarily increase lead levels. Older infrastructure continues to pose a risk.
Understanding Lead Filtration Technologies
Several technologies effectively remove lead from drinking water, each operating through a distinct mechanism. Reverse osmosis (RO) systems force water through a semi-permeable membrane at high pressure. This membrane blocks larger contaminants, including dissolved lead ions, which are then flushed away. RO systems are typically installed at a single tap, such as under the kitchen sink, and are known for their high effectiveness in removing a wide range of impurities.
Activated carbon filters, particularly solid carbon block filters, can significantly reduce lead. These filters use adsorption, where lead particles and other contaminants stick to the surface of the porous carbon material. The intricate network of pores within the carbon traps lead as water flows through, effectively removing it. Granular activated carbon filters are generally less effective for lead removal than block carbon filters.
Distillation purifies water by heating it to create steam, leaving behind lead and other heavy metals. The steam then condenses back into liquid water, resulting in highly purified water. This process effectively removes lead, though it is often slower and requires more energy than other filtration methods.
Ion exchange filters operate by swapping undesirable ions, such as lead, with less harmful ions, typically sodium or potassium, that are bound to a resin. As lead-contaminated water passes through, lead ions are attracted to the resin and exchange places with the bound ions. This process effectively captures lead within the filter material, reducing its concentration.
Choosing and Maintaining Lead Filters
When selecting a lead water filter, prioritizing products with third-party certifications is important. Certifications from organizations like NSF International indicate that a filter has been independently tested and verified to meet specific performance standards for lead removal. For lead, look for filters certified to NSF/ANSI Standard 53 for lead reduction or NSF/ANSI Standard 58, which covers reverse osmosis systems that also remove lead. These certifications confirm the filter’s ability to reduce lead to safe levels.
Filters are available in various types based on their installation point. Point-of-use (POU) filters are installed at a specific tap, like a kitchen faucet or on a pitcher, providing filtered water directly where it is consumed. Point-of-entry (POE) or whole-house filters are installed where the main water line enters the home, treating all water. While POE filters offer comprehensive treatment, POU filters are often more cost-effective for solely addressing lead in drinking water.
Proper maintenance is necessary to ensure the continuous effectiveness of any lead filter. All filters have a finite capacity for contaminants, and their effectiveness diminishes over time as they become saturated. Following the manufacturer’s recommended replacement schedule for filter cartridges is essential, as neglecting replacement can lead to reduced performance and potential re-release of contaminants. Regular cleaning of faucet aerators also contributes to overall lead safety.
Additional Lead Safety Measures
Beyond filtration, several simple practices can further reduce potential lead exposure from drinking water. One practice involves flushing cold water taps before use, especially if the water has been sitting in the pipes for several hours. Running the cold water for at least 30 seconds to a few minutes can help clear out water that may have absorbed lead from pipes and fixtures. This action brings fresh water from the main into the home’s tap.
Always use cold water for drinking, cooking, and preparing baby formula. Hot water can dissolve lead from plumbing materials more quickly than cold water, potentially leading to higher lead concentrations. Even if a home does not have lead pipes, using cold water is a recommended precaution.
A common misconception is that boiling water removes lead; however, boiling water does not remove lead and can actually increase its concentration due to water evaporation. Boiling water only concentrates lead that is already present, making the water potentially more harmful. Therefore, boiling is not an effective method for lead removal.
Consider having your water tested for lead, especially if your home was built before 1986 or if you suspect lead plumbing. Lead is odorless, tasteless, and invisible in water, so testing is the only way to confirm its presence and concentration. Many local health departments or water suppliers can provide information on certified laboratories for water testing.
How Lead Enters Drinking Water
Lead typically enters drinking water through the corrosion of plumbing materials within a home or service line, rather than being present in the water source itself. This corrosion, a chemical reaction between water and lead-containing metals, is more pronounced when water has high acidity or low mineral content. Lead service lines, connecting a home to the public water main, are common points of entry, especially in older cities and homes built before 1986.
Household plumbing can also contribute to lead contamination. Lead solder, used to join copper pipes before 1987, is a significant source. Newer brass faucets and fixtures can leach lead into water, especially when water sits in them for several hours. Galvanized iron pipes, installed before the 1960s, can also attract and release lead particles if a lead service pipe was present.
When water remains stagnant in pipes or fixtures for extended periods, such as overnight, it has more time to dissolve lead. This can lead to higher lead concentrations in the first draw of water. Disturbing lead pipes, such as during plumbing repairs, can also temporarily increase lead levels. Older infrastructure continues to pose a risk.
Understanding Lead Filtration Technologies
Several technologies effectively remove lead from drinking water, each operating through a distinct mechanism. Reverse osmosis (RO) systems force water through a semi-permeable membrane at high pressure. This membrane blocks larger contaminants, including dissolved lead ions, which are then flushed away. RO systems are typically installed at a single tap, such as under the kitchen sink, and are known for their high effectiveness in removing a wide range of impurities.
Activated carbon filters, particularly solid carbon block filters, can significantly reduce lead. These filters use adsorption, where lead particles and other contaminants stick to the surface of the porous carbon material. The intricate network of pores within the carbon traps lead as water flows through, effectively removing it. Granular activated carbon filters are generally less effective for lead removal than block carbon filters.
Distillation purifies water by heating it to create steam, leaving behind lead and other heavy metals. The steam then condenses back into liquid water, resulting in highly purified water. This process effectively removes lead, though it is often slower and requires more energy than other filtration methods.
Ion exchange filters operate by swapping undesirable ions, such as lead, with less harmful ions, typically sodium or potassium, that are bound to a resin. As lead-contaminated water passes through, lead ions are attracted to the resin and exchange places with the bound ions. This process effectively captures lead within the filter material, reducing its concentration.