Copper is a naturally occurring metal and an essential nutrient, but drinking water can contain excessive amounts of copper when plumbing materials corrode.
In many homes, the primary source is not the lake, reservoir, or groundwater supplying the property. Instead, copper can enter the water as it sits in or passes through copper pipes, fittings, and fixtures.
Quick answer: EPA uses a copper action level of 1.3 mg/L, or 1,300 µg/L, under the Lead and Copper Rule. Copper commonly enters drinking water through corrosion of household plumbing. Blue-green staining, metallic or bitter taste, and pinhole leaks can suggest a corrosion problem, but laboratory testing is the appropriate way to measure the copper concentration.
In This Guide
- What Is Copper?
- How Copper Gets Into Water
- What Causes Copper Corrosion?
- Signs of Copper in Water
- Health Effects
- EPA Copper Action Level
- Wilson Disease
- How to Test for Copper
- Does Flushing Help?
- Why Use Cold Water?
- Private Wells
- Public Water Systems
- Treatment Options
- Where Berkey® Fits
- Frequently Asked Questions
What Is Copper?
Copper is a naturally occurring metallic element found in rocks, soil, water, plants, animals, and food.
The human body needs small amounts of copper for normal functions involving:
- Iron metabolism
- Connective tissue
- Energy production
- Nervous-system function
Most copper intake normally comes from food.
Copper is essential, but essential does not mean unlimited amounts are harmless. Excessive exposure can cause adverse effects.
How Does Copper Get Into Drinking Water?
Copper can occur naturally in source water, but corrosion of plumbing materials is one of the most important household sources.
Potential contributors include:
- Copper pipes
- Copper fittings
- Brass plumbing components
- Water that has remained stagnant in plumbing
EPA identifies corrosion of household plumbing systems as a principal source of copper in drinking water. :contentReference[oaicite:3]{index=3}
Why Does Water Sitting in Pipes Matter?
When water remains in plumbing for several hours, it has more time to interact with metal surfaces.
Copper concentrations can therefore sometimes be higher:
- First thing in the morning
- After returning from vacation
- At an infrequently used faucet
CDC notes that long periods of low or no building water use can increase corrosion-related release of copper and other metals. :contentReference[oaicite:4]{index=4}
What Causes Copper Pipe Corrosion?
Corrosion is influenced by water chemistry, plumbing design, temperature, and other conditions.
Factors can include:
- pH
- Alkalinity
- Dissolved oxygen
- Water temperature
- Mineral content
- Water velocity
- Pipe age
- Installation quality
- Stagnation time
Is Low pH the Only Cause?
No.
Acidic water can contribute to metal corrosion, but copper corrosion is more complex than simply saying “pH below 7 causes copper problems.”
Water chemistry and plumbing materials interact in different ways, and corrosion control in public systems is designed around those site-specific conditions.
I would remove the old DIY electrical-grounding and jumper-cable instructions. Electrical bonding and grounding of plumbing systems are building-code and electrical-safety matters that should be evaluated by qualified professionals rather than treated as a household water-quality repair.
What Are Signs of Copper Corrosion?
Possible signs include:
- Blue or blue-green staining around sinks, tubs, or fixtures
- Metallic or bitter taste
- Blue-green deposits
- Pitting of copper pipes
- Pinhole leaks
Minnesota's health department identifies pinhole leaks, pitting, and blue-green staining as possible signs of corrosive water. :contentReference[oaicite:5]{index=5}
Staining cannot tell you the copper concentration. A blue-green stain is a reason to investigate water chemistry and plumbing, not proof that the drinking water is above EPA's action level.
Can Too Much Copper in Drinking Water Be Harmful?
Yes.
High copper exposure can cause gastrointestinal effects such as:
- Nausea
- Vomiting
- Diarrhea
- Abdominal or stomach pain
EPA also identifies possible liver or kidney damage from longer-term excessive exposure. :contentReference[oaicite:6]{index=6}
Most healthy people regulate copper efficiently, but susceptibility differs among individuals. Minnesota health officials note that people with Wilson disease and some infants may be more sensitive to excessive copper exposure. :contentReference[oaicite:7]{index=7}
What Is EPA's Copper Limit?
This needs an important clarification.
EPA does not regulate copper in public drinking water through an ordinary MCL, as it does for contaminants such as arsenic.
Copper is regulated under the Lead and Copper Rule using a treatment technique and an action level of:
1.3 mg/L = 1,300 µg/L = 1.3 ppm
Public water systems sample customer taps.
If more than 10% of sampled taps exceed 1.3 mg/L—equivalent to the system's 90th-percentile result exceeding the action level—the system must undertake additional corrosion-control or regulatory actions. :contentReference[oaicite:8]{index=8}
This is not the same as saying every tap above 1.3 mg/L automatically puts the entire water system in violation. The Lead and Copper Rule evaluates the system through tap sampling and a 90th-percentile calculation.
Copper and Wilson Disease
Wilson disease is a rare inherited disorder involving abnormal copper metabolism.
People with the condition have difficulty eliminating copper and can accumulate excessive amounts in the liver and other tissues.
Copper in drinking water does not cause Wilson disease. Wilson disease is genetic. However, people with the condition may be more vulnerable to copper exposure because their bodies cannot regulate copper levels normally.
ATSDR describes Wilson disease as an autosomal recessive disorder involving impaired biliary excretion of copper. :contentReference[oaicite:9]{index=9}
If someone in the household has Wilson disease, follow their physician's guidance about copper intake and drinking water.
How Do You Test Drinking Water for Copper?
If copper is a concern, the most useful test is a properly collected tap-water sample analyzed by an accredited drinking-water laboratory.
The laboratory can advise you about:
- Sampling bottles
- Stagnation time
- First-draw versus flushed samples
- Preservation
- Sample handling
Blood or urine copper testing and drinking-water testing answer different questions. A physician may order medical tests when clinically appropriate, while a water laboratory measures the copper concentration at your tap.
I would remove the article's discussion of hair analysis. It is not necessary for answering the drinking-water question.
Does Flushing the Faucet Reduce Copper?
It can occur when copper enters water from household plumbing.
Minnesota health guidance recommends running the water for 30 to 60 seconds before using it for drinking or cooking if the faucet has not been used for more than 6 hours. :contentReference[oaicite:10]{index=10}
CDC similarly recommends flushing stagnant water when copper plumbing is the source of contamination. :contentReference[oaicite:11]{index=11}
Flushing is a practical exposure-reduction step, not a repair for corrosion. If copper repeatedly returns at elevated concentrations, investigate the underlying plumbing or water-chemistry problem.
Why Should You Use Cold Water for Drinking and Cooking?
Hot water can dissolve copper from plumbing more readily than cold water.
For drinking, cooking, and preparing infant formula:
Use fresh cold tap water and heat it separately if hot water is needed.
This recommendation is also consistent with current public health guidance on copper exposure from plumbing.
Copper and Private Well Water
The original article says copper is not found in groundwater from wells. That is too absolute.
Copper can occur naturally in source water, although household plumbing is often the more important source in homes with copper components.
For private wells, consider both:
- The chemistry of the groundwater
- What happens after that water enters household plumbing
Corrosive groundwater can increase metal release from household pipes and fixtures.
When Should a Well Owner Test?
Copper testing may be useful when:
- Blue-green staining appears.
- Pinhole leaks develop.
- Water has a persistent metallic or bitter taste.
- The home's plumbing is primarily copper.
- Water chemistry changes after a new well is installed.
- Other corrosion problems are present.
Copper and Public Water Systems
Public systems subject to the Lead and Copper Rule monitor customer taps rather than simply measuring copper at the treatment plant.
This is important because copper may enter the water after treatment as it travels through building plumbing.
Check Your Consumer Confidence Report
Your community's water-quality report may show:
- The 90th-percentile copper result
- EPA's 1.3-mg/L action level
- The number of samples exceeding the action level
Your home's concentration can still differ from the reported system-wide sampling result because every plumbing system is different.
How Can Copper Be Reduced in Drinking Water?
Treatment depends on where the copper is coming from.
| Cause | Possible Response |
|---|---|
| Stagnant water in copper plumbing | Flush the cold tap before drinking or cooking |
| Corrosive water chemistry | Evaluate corrosion control or neutralization |
| Deteriorating plumbing | Repair or replace affected plumbing |
| Copper at the drinking-water tap | Use an appropriately tested or certified point-of-use treatment system |
Reverse Osmosis
Reverse osmosis can reduce dissolved copper when the system is designed and maintained for that purpose.
Ion Exchange
Specialized ion-exchange media can reduce selected dissolved metals, including copper, depending on system design and water chemistry.
Distillation
Distillation can separate many dissolved minerals and metals from water.
CDC identifies reverse osmosis, ultrafiltration, distillation, and ion exchange among treatment technologies used for copper reduction.
Do not choose treatment based only on the label “carbon filter” or “gravity filter.” Look for copper-specific testing or certification for the exact filter element.
Where Do Berkey® Water Filters Fit?
Berkey® water filter systems are gravity-fed countertop systems.
The stainless-steel chamber determines:
- Water capacity
- Countertop footprint
- Compatible filter configuration
The installed filter element determines contaminant-reduction performance.
If copper is your concern, review the current copper-specific test data for the filter element rather than assuming that every Berkey® configuration yields the same result.
For current filter information, see:
I would remove the old claim that all Berkey® filters have simply been “proven to remove copper” unless the statement is tied directly to current element-specific test documentation.
What Should You Do If Copper Tests Above 1.3 mg/L?
If a properly collected tap-water sample shows copper above 1.3 mg/L:
- Confirm the result with the laboratory or an appropriate follow-up test.
- Use fresh cold water for drinking and cooking.
- Flush stagnant plumbing before use.
- Contact your water utility if you receive public water.
- Have the plumbing and water chemistry evaluated if corrosion is suspected.
- Consider an appropriately tested treatment system if needed.
People with Wilson disease should follow their physician's guidance if their drinking water has elevated copper levels. EPA specifically advises people with Wilson disease to consult their doctor if copper exceeds the action level.
Frequently Asked Questions About Copper in Drinking Water
How does copper get into drinking water?
Copper often enters drinking water through corrosion of copper pipes, fittings, and other household plumbing materials. It can also occur naturally in source water.
What is EPA's copper limit?
EPA sets a copper action level of 1.3 mg/L (1,300 µg/L) under the Lead and Copper Rule.
Is 1.3 mg/L a Maximum Contaminant Level?
No. Copper is regulated through a treatment technique under the Lead and Copper Rule rather than an ordinary MCL. The 1.3-mg/L value is the action level.
What does the copper 90th percentile mean?
Public systems sample multiple customer taps. If the 90th-percentile copper value exceeds 1.3 mg/L, more than 10% of sampled taps exceed the action level, triggering additional regulatory actions.
Can copper make water taste metallic?
Yes. Higher dissolved copper concentrations can contribute to a metallic or bitter taste, although taste cannot determine the exact concentration.
What causes blue-green stains?
Copper corrosion products can produce blue-green staining on sinks, tubs, and fixtures. Testing is still needed to determine the copper concentration in drinking water.
Are blue-green stains proof that the water is above 1.3 mg/L?
No. They suggest copper corrosion may be occurring but do not establish the drinking-water concentration.
Is copper harmful to health?
Copper is an essential nutrient, but excessive intake can cause gastrointestinal symptoms and, at sufficiently high or prolonged exposures, liver or kidney effects.
Does copper cause Wilson disease?
No. Wilson disease is an inherited disorder of copper metabolism. People with the condition are more susceptible to copper accumulation.
Does flushing the faucet reduce copper?
It can when plumbing is the source. Running fresh cold water after a faucet has been unused for several hours can reduce exposure to water that has been in prolonged contact with copper pipes.
Should I drink hot tap water?
For drinking and cooking, use fresh cold tap water and heat it separately. Hot water can more readily dissolve copper and other metals from plumbing.
Can private wells contain copper?
Yes. Copper can occur in source water, but in many homes the more significant source is corrosion of plumbing after well water enters the building.
How do I test for copper in my water?
Use an accredited drinking-water laboratory and follow its sampling instructions. Depending on the question being investigated, first-draw and flushed samples may provide different information.
Can a TDS meter measure copper?
No. A household TDS meter cannot identify copper or determine its concentration.
Does reverse osmosis reduce copper?
Appropriately designed reverse osmosis systems can reduce dissolved copper levels. Review contaminant-specific performance for the exact system.
Does activated carbon remove copper?
Plain activated carbon should not automatically be assumed to provide reliable copper reduction. Finished filters may include additional media specifically designed and tested for metals.
Can a Berkey® filter reduce copper?
Performance depends on the specific filter element installed. Review current copper-specific test data for the element rather than relying on the Berkey® chamber size alone.
Final Thoughts
Copper in drinking water is usually best understood as a plumbing and corrosion problem rather than simply a source-water contaminant.
The most useful clues include:
- Blue-green staining
- Metallic or bitter taste
- Pinhole leaks
- Copper plumbing
- Water that has remained stagnant for long periods
But none of those clues can replace an actual water test.
If copper is a concern, test the water first, determine whether household plumbing is the source, correct corrosion where practical, and choose treatment based on copper-specific performance.