Where does lead contamination in water primarily come from?

The primary source of lead contamination in water is indeed from solder, brass fittings and fixtures, and service lines. These components often contain lead or have leaded materials. When water sits in these pipes for extended periods, lead can leach from them into the water supply. This is particularly problematic in older plumbing systems where lead solder was commonly used prior to regulatory changes that limited lead in plumbing materials.

Lead pipes, while a historical source, have largely been replaced and are not the primary issue for most residential water supplies today, particularly in newer constructions. Paint and varnish, while significant sources of lead exposure, are primarily related to inhalation or ingestion of lead dust and chips rather than direct water contamination. Similarly, the decay of lead-based products affects indoor air quality and surface exposure but is not a direct source of lead in drinking water.

Thus, knowing that solder and fixtures in plumbing systems are the most common pathways for lead to enter drinking water supplies provides critical context for understanding lead exposure risks in residential water.