Lead contamination in drinking water is a significant public health concern, often resulting from the corrosion of lead service lines and older plumbing. Even low levels of lead exposure can cause serious, long-term health effects, especially in children and pregnant individuals. Since there is no known safe level of lead, many people seek effective methods to purify their tap water at home. Distillation, a process that mimics the natural water cycle, is often presented as a potential solution.
Understanding the Distillation Process
Distillation’s effectiveness against lead relies on the fundamental difference in the physical properties of water and the heavy metal. The process begins by heating the contaminated source water until it vaporizes into steam.
As water vaporizes, it leaves behind contaminants that do not readily turn into a gas. Lead has an extremely high boiling point of approximately 3,180°F (1,750°C), while water boils at 212°F (100°C). Since a home distiller’s temperature never approaches lead’s boiling point, the metal cannot evaporate with the water.
The steam is then collected and cooled in a separate chamber, where it condenses back into purified water. The lead, along with other non-volatile inorganic minerals and salts, remains trapped in the original boiling chamber. This separation based on boiling point ensures lead is effectively excluded from the final product.
Measured Effectiveness in Lead Removal
Distillation is consistently cited as one of the most effective methods for purifying water. The process is proven to remove a wide spectrum of contaminants, including heavy metals like lead, with extremely high efficiency. Most sources indicate that water distillers remove 99.9% or more of impurities and dissolved solids from the source water.
This high degree of purification ensures the resulting water meets or exceeds strict standards for lead contamination. The U.S. Environmental Protection Agency (EPA) sets the maximum contaminant level goal for lead in drinking water at zero. Distilled water can achieve a purity level that is virtually free of lead, providing a significantly safer option for consumption.
Practical Considerations for Home Use
While distillation is scientifically sound for lead removal, using a home unit involves certain practical trade-offs. The process is inherently slow, with typical home distillers producing only a few gallons per day. This slow output is also energy-intensive, as the unit must continuously boil water for hours, resulting in a noticeable operating cost.
Regular maintenance is necessary to ensure the distiller maintains high removal efficiency. The lead and other concentrated inorganic contaminants left behind form a residue that must be cleaned out periodically. Depending on the source water quality, this cleaning may be required every few weeks to prevent mineral buildup that could reduce performance.
A significant limitation of distillation is its variable effectiveness against Volatile Organic Compounds (VOCs). Certain VOCs, such as benzene or toluene, have boiling points close to or lower than water, allowing them to vaporize along with the steam. To achieve complete water purity, many home distillation systems incorporate a final stage of activated carbon filtration to capture any VOCs that carry over.