Copper in Drinking Water
Copper enters drinking water primarily from copper household plumbing and service lines — not from the water source itself. It is regulated under the same Lead and Copper Rule as lead. At low levels, copper is an essential nutrient. At elevated levels (above 1.3 mg/L), it causes gastrointestinal symptoms acutely and liver and kidney damage with chronic exposure. Blue-green staining on sinks and fixtures is the most common sign of elevated copper. Corrosive (low-pH, low-alkalinity) water dramatically accelerates copper leaching.
Quick Answer
Copper (Cu) plumbing became the standard in U.S. residential construction from the 1960s onward, replacing lead and galvanized steel pipes. Unlike lead service lines, copper plumbing is still installed today — but copper can still dissolve into drinking water when water chemistry is corrosive. The EPA regulates copper under the Lead and Copper Rule (LCR), which sets an action level of 1.3 mg/L: if more than 10% of first-draw tap samples exceed this level, utilities must take corrosion control action. The same rule covers [lead](/contaminants/lead), which is addressed through the same corrosion control programs.
Why Is Copper in Drinking Water a Concern?
Copper contamination at the tap can be significant even when a utility's source water contains no detectable copper — because the problem originates in home plumbing, not the utility system. Newly installed copper plumbing leaches the most copper, with leaching declining over years as a protective oxide layer forms. Acidic water (pH below 7), soft water (low mineral content), and hot water all dramatically accelerate copper leaching. Homes with copper plumbing and aggressive (low-pH, high-chloramine) water chemistry can see copper levels well above the action level at the kitchen tap.
Homes with copper plumbing — the vast majority of homes built after 1960 — have some copper exposure, though most is at safe levels. Homes with acidic or soft water are at highest risk of elevated copper. Infants under 1 year are the most sensitive population — the EPA's maximum contaminant level goal (MCLG) for infant formula preparation is effectively 1.3 mg/L. People with Wilson's disease (a genetic disorder of copper metabolism) face greater risk at lower copper levels. Residents whose utility has switched from chlorine to chloramine as a disinfectant may see increased copper leaching, as chloramine can be more corrosive to copper under some water chemistry conditions.
Health Effects of Copper in Drinking Water
Acute gastrointestinal symptoms at elevated levels: nausea, vomiting, stomach cramps, and diarrhea — typically from water above 1–2 mg/L
Blue-green staining on sinks, fixtures, and laundry — the most commonly noticed indicator of elevated copper
Liver and kidney damage with long-term chronic exposure above the action level
Copper toxicosis in infants: Wilson's disease patients and infants under 1 year are most sensitive
At levels below the 1.3 mg/L action level, copper is an essential nutrient — deficiency is possible at very low dietary intake
Hair discoloration (greenish tint) with regular exposure in shower water at elevated concentrations
How Does Copper Get Into Drinking Water?
Copper household plumbing — the dominant source; copper dissolves into water as it sits in pipes
Copper service lines — less common than copper household plumbing but present in some older systems
Lead-free brass faucets and fittings — allowed to contain up to 0.25% lead and some copper
Corrosive water chemistry — low pH (below 7.0), soft water, and high chloramine accelerate copper leaching
New copper plumbing — leaches the most in the first 1–2 years before a protective patina forms
Hot water heaters and boilers with copper components
Regulatory Limit
EPA Maximum Contaminant Level (MCL)
1.3 mg/L (action level)
The EPA regulates copper under the Lead and Copper Rule (LCR) with an action level of 1.3 mg/L — if more than 10% of first-draw tap samples exceed this, utilities must implement corrosion control treatment. The MCLG is 1.3 mg/L (unlike lead, where the MCLG is zero). The 2024 Lead and Copper Rule Improvements (LCRI) strengthened corrosion control requirements that also benefit copper reduction. Unlike lead, the copper action level was not lowered in the 2024 revisions. Individual taps can exceed 1.3 mg/L even when the utility is in overall compliance.
How to Test for Copper in Your Water
Copper testing requires a first-draw sample — water that has sat in contact with plumbing for at least 6 hours, collected before running the tap. Certified lab tests cost $20–$40 for copper alone. Blue-green staining on white porcelain sinks is a strong indicator of copper above approximately 0.5–1 mg/L and should prompt testing. Many utilities offer free tap testing upon request. Because copper comes from your plumbing rather than the source water, utility-wide compliance data does not reflect what is coming out of your specific tap.
How to Remove Copper from Drinking Water
These treatment methods have demonstrated effectiveness for Copper removal.
Reverse Osmosis
Reverse osmosis (RO) is the most comprehensive point-of-use water treatment technology available for residential use. It removes 90–99% of dissolved contaminants including PFAS, lead, arsenic, nitrates, and disinfection byproducts by forcing water through a semi-permeable membrane with pores of approximately 0.0001 microns.
Activated Carbon
Activated carbon is the most widely used residential water treatment technology. It removes chlorine, taste and odor compounds, disinfection byproducts, many volatile organic compounds (VOCs), and — with NSF/ANSI 53 certification — lead and some PFAS. It is available as pitcher filters, under-sink units, and whole-house systems.
Frequently Asked Questions
Related Pages
Data Sources & Provenance
All data on this page is sourced from official U.S. government or public datasets.
Quick Reference
Category
Heavy Metals
Risk Level
moderate
EPA Limit
1.3 mg/L (action level)
Most at Risk
Homes with copper plumbing — the vast majority of homes built after 1960 — have some copper exposure, though most is at safe levels.
Well Water Relevant
No
Copper by State
Treatment Options