7 Core Drinking Water Contaminants

National Exposure Statistics

98%

Americans have detectable PFAS in their blood (EWG analysis)

9.2M

Lead service pipes still in use across the United States

200M+

Americans drink water with contaminant levels exceeding health guidelines

Contaminant Risk Profile Summary

Seven major categories of drinking water contaminants with verified data on sources, core health hazards, and key exposure characteristics.

Arsenic (Traditional)

Arsenic (Traditional)

Source

Natural geological release, hard rock mining contamination

Core Health Hazards

• • Confirmed human carcinogen (skin, bladder, lung cancer)

• • Associated with cardiovascular disease, birth defects, neurodevelopmental damage

• • Cancer risk persists below 10μg/L

Key Exposure Characteristics

• • High concentrations in Southwest and Northeast US

• • Hispanic, Native American, low-income communities face higher exposure

• • Private wells pose greater risk than public systems

Disinfection Byproducts (DBPs)

Disinfection Byproducts (DBPs)

Source: Generated when disinfectants react with organic matter and bromide during water treatment; approximately 700 types identified

Core Health Hazards

• • Long-term exposure linked to bladder cancer, reproductive developmental abnormalities

• • Iodinated and nitrogenous DBPs far more toxic than regulated types

Key Exposure Characteristics

• • Surface water concentrations > groundwater

• • Higher concentrations in summer and at pipe network endpoints

• • Small systems exceed standards more frequently

Lead (Traditional)

Lead (Traditional)

Source: Corrosion of aging lead pipes, solder, and brass fittings; 9.2 million lead service pipes still exist nationwide

Core Health Hazards

• • Systemic toxicity, severely damages children's neurodevelopment (IQ reduction)

• • Linked to cancer, kidney damage, birth defects

• • No safe exposure level

Key Exposure Characteristics

• • Release intensifies during high summer water temperatures and stagnation (schools/daycare centers)

• • Higher exceedance rates in minority and low-income communities

Nitrates (Traditional)

Nitrates (Traditional)

Source: Agricultural fertilizers, livestock farming, septic tanks, wastewater treatment discharge

Core Health Hazards

• • Causes infant methemoglobinemia (blue baby syndrome)

• • Converts to carcinogenic nitrites in the body

• • Linked to birth defects, colorectal cancer, thyroid disease

• • Risk persists below 10mg/L

Key Exposure Characteristics

• • Highest concentrations in shallow private wells in agricultural areas

• • Significantly elevated exposure in Hispanic communities

PFAS (Emerging, Forever Chemicals)

PFAS (Emerging, Forever Chemicals)

Source: Industrial production, firefighting foam, food packaging, landfill leachate; 14,700+ types identified, environmentally persistent

Core Health Hazards

• • Immune toxicity, lipid abnormalities, thyroid disruption, low birth weight

• • Testicular/kidney cancer

• • Detectable in 98% of Americans' blood

Key Exposure Characteristics

• • Highest concentrations near industrial/military/airport sites

• • Higher exposure in communities of color

• • Private well risks underestimated

Uranium (Traditional/Emerging Crossover)

Uranium (Traditional/Emerging Crossover)

Source: Natural geological release, uranium mining, phosphate fertilizer production, military activities

Core Health Hazards

• • Nephrotoxicity, radiological carcinogenesis

• • Linked to cardiovascular, neurological, reproductive damage

• • Indigenous populations face elevated risks

Key Exposure Characteristics

• • High concentrations in Central and Southwest US

• • Groundwater > surface water

• • Navajo Nation exposure 2.67-2.8 times higher than general population

Data Sources & Official Resources

Reference: US drinking water quality: exposure risk profiles for seven legacy and emerging contaminants

U.S. EPA Water Data

Access Safe Drinking Water Information System (SDWIS) and Enforcement and Compliance History Online (ECHO).

epa.gov/sdwis

CDC Healthy Water

Centers for Disease Control resources on waterborne diseases, contaminants, and health effects.

cdc.gov/healthywater

USGS Water Quality

U.S. Geological Survey's National Water Quality Assessment program with comprehensive monitoring data.

usgs.gov/water

EWG Tap Water Database

Environmental Working Group's database of contaminants found in tap water across all 50 states.

ewg.org/tapwater

NRDC Water Reports

Natural Resources Defense Council investigations and policy reports on water quality issues.

nrdc.org/water

Consumer Confidence Reports

Annual water quality reports from local utilities required under the Safe Drinking Water Act.

epa.gov/ccr