Lead in Drinking Water: Health Effects, Sources, and Treatment
- Natural Tap Water
- Jan 26
- 3 min read
Introduction
Lead is a highly toxic heavy metal with no safe level of exposure for humans. Its presence in drinking water, primarily due to the corrosion of plumbing materials, represents a significant and preventable public health risk, particularly for children and pregnant women.
Contaminant Profile
Lead (Pb) is a post-transition metal in Group 14 of the periodic table. It is a soft, dense, and malleable metal with a bluish-white color when freshly cut, which quickly tarnishes to a dull gray upon exposure to air.
Chemical Profile:
Formula: Pb
CAS Number: 7439-92-1
Atomic Number: 82
Atomic Weight: 207.2 u
Physical Properties:
Appearance: Bluish-gray metallic solid
Density: 11.34 g/cm³
Melting Point: 327.5 °C (621.5 °F)
Boiling Point: 1749 °C (3180 °F)
Solubility: Insoluble as a metal, but some lead compounds can dissolve
Sources and Pathways into Water
Lead rarely occurs naturally in source water. Its primary pathway into drinking water is through the corrosion of man-made materials in water distribution systems.
Natural Sources:
Lead can be found in the Earths crust in mineral deposits, but it is not a significant source in treated drinking water.
Man-Made Sources:
Lead Service Lines (LSLs): Pipes connecting older homes (built before 1986) to the public water main - the most significant source
Lead Solder: Used to join copper pipes, common in homes built before the 1986 lead ban
Brass Fixtures: Faucets and fittings made of brass can contain lead, which leaches into water
Environmental Fate:
Lead is a persistent element that does not degrade. It can bioaccumulate in the body, primarily in bones, over a persons lifetime. Water corrosivity (pH, alkalinity, temperature) determines how much lead leaches from pipes.
Human Health Effects
There is no safe level of lead in the human body. It is a potent neurotoxin that can cause irreversible damage, particularly in developing brains.
Acute Health Effects:
High exposure can cause lead poisoning with symptoms including abdominal pain, constipation, fatigue, headaches, and in severe cases, seizures, coma, and death.
Chronic Health Effects:
In Children: Behavioral and learning problems, lower IQ, hyperactivity, slowed growth, hearing problems, anemia
In Pregnant Women: Reduced fetal growth, premature birth. Lead crosses the placental barrier and can be transmitted through breast milk
In Adults: Cardiovascular effects (hypertension), decreased kidney function, reproductive problems
Carcinogenicity:
U.S. EPA: Group B2 - Probable Human Carcinogen
IARC: Group 2A - Probably Carcinogenic to Humans
Vulnerable Populations:
Fetuses, infants, and young children are most vulnerable because their brains and nervous systems are still developing. They absorb lead more readily than adults.
Treatment and Removal
Lead cannot be removed by boiling water; in fact, boiling can increase its concentration.
Municipal Treatment:
Public water systems address lead by managing water chemistry to make it less corrosive. This involves adding corrosion inhibitors (like orthophosphates) that form a protective coating inside pipes.
Home Treatment Options:
Reverse Osmosis (NSF/ANSI 58): High effectiveness (>99%)
Activated Carbon (NSF/ANSI 53): High effectiveness when certified for lead reduction
Distillation (NSF/ANSI 62): High effectiveness
Occurrence and Case Studies
Prevalence:
An estimated 9 million lead service lines are still in use across the United States. Homes built before 1986 are at the highest risk.
Case Study - Flint, Michigan (2014-2019):
In April 2014, the city of Flint switched its water source to the highly corrosive Flint River without implementing corrosion control treatment. This caused lead from the citys aging pipes to leach into the drinking water, exposing tens of thousands of residents to dangerous lead levels. The crisis resulted in widespread lead poisoning, particularly among children, and was linked to an outbreak of Legionnaires disease that killed at least 12 people. The event became a symbol of infrastructure failure and environmental injustice in the United States.