The question of whether lead dissolves in water is complex, involving the chemistry of corrosion and the materials used in aging infrastructure. While pure lead does not simply dissolve like table salt, the metal enters the water supply through a different chemical process. Understanding this lead release is important for public health because even low levels of exposure can be harmful, particularly to children. The presence of lead in drinking water is primarily an issue of material science and water treatment, not a failure of the water source itself.
The Chemical Reality: Lead and Water Solubility
Lead is technically considered insoluble in water, meaning it does not readily dissolve to form a homogenous solution in its elemental state. If you placed a piece of pure lead metal into distilled water, very little of the metal would truly dissolve. Instead, the problem is related to corrosion, which is the wearing away of the metal caused by a reaction with water and dissolved oxygen.
This process releases lead into the water as lead ions or small particulate solids, not as dissolved metal. The lead ions then react with naturally occurring compounds, such as carbonates, to form solid corrosion products like lead carbonate. Although lead carbonate is highly insoluble, the chemical attack on the pipe’s interior surface introduces lead particles and ions into the flowing water stream.
How Lead Enters Drinking Water Systems
The source of lead contamination is almost universally the plumbing materials that transport the water once it reaches a building. The most common source is the lead service line (LSL), which connects the municipal water main to the home’s internal plumbing. Although lead pipes were banned decades ago, millions of these lines remain active, especially in older cities and homes built before the late 1980s.
Other sources include lead-based solder used to join copper pipes (banned in 1986) and brass or bronze fixtures, which can contain small amounts of lead. Corrosion begins when the protective mineral scale, which naturally forms inside these pipes, is disrupted by the water chemistry. This exposes the underlying lead metal, allowing lead to leach into the water as dissolved ions or erode as fine particles.
Galvanized iron pipes, sometimes found in older homes, can also accumulate lead deposits from other parts of the system. As the galvanized pipe corrodes, these accumulated lead particles can be released into the drinking water.
Water Chemistry Factors That Increase Lead Release
Several characteristics of the water influence the rate and extent of lead release from plumbing materials. The water’s pH, which measures its acidity or alkalinity, is a major factor; lower pH water is more acidic and tends to be more corrosive to lead pipes. Water with low mineral content, often described as “soft” water, can also be particularly corrosive because it lacks the dissolved minerals needed to form a stable, protective coating on the pipe walls.
Temperature also plays a role, as hot water accelerates chemical reactions, leading to faster corrosion and higher lead levels. Furthermore, stagnation, the amount of time water sits motionless, allows for greater interaction time between the water and the pipes, increasing the concentration of lead that accumulates. To manage this, many municipalities implement corrosion control treatments, such as adding orthophosphates. These chemicals encourage the formation of a stable, low-solubility lead-phosphate layer on the pipe’s interior, reducing lead release.
Health Risks and Mitigation Strategies
Exposure to lead, even at low levels, is associated with a range of serious health effects, as no safe blood lead level has been identified. The developing nervous system of young children and fetuses is particularly vulnerable, with exposure linked to reduced intelligence quotient (IQ), learning disabilities, and behavioral problems. In adults, long-term exposure is connected to high blood pressure, cardiovascular problems, and decreased kidney function.
Because lead exposure is preventable, homeowners can take several practical steps to reduce their risk. The most definitive step is to have the water tested by a certified laboratory, especially if the home was built before 1986. Always use only cold water for drinking, cooking, and preparing baby formula, since hot water can contain higher lead concentrations.
If your plumbing contains lead, you can significantly reduce exposure by flushing the water—running the cold water tap for thirty seconds to two minutes—any time the water has been sitting in the pipes for several hours. For a more permanent solution, certified water filters, such as those with carbon block technology, can effectively remove lead. It is important to choose a filter certified for lead removal and to replace the cartridge on schedule.