Copper in Tap Water: Why Newer Plumbing Is the Usual Suspect, and How to Check Your Tap
Copper in tap water usually doesn’t come from the river or reservoir. It comes from the house itself, and ATSDR says high levels are more likely in new or recently renovated buildings using copper plumbing. You may have just moved into a remodel, or noticed blue-green stains on a sink or a metallic taste in your morning glass. By the end, you’ll know how to read the warning signs, flush your pipes correctly, get the right test, and decide when to bring in a doctor.
Where the copper comes from
Copper is an element and metal found in rocks, soils, water, and air. It’s also an essential nutrient that your body needs from many foods. You’ll find it in wiring, plumbing, pesticides, cookware, and dietary supplements. ATSDR is clear that you need small amounts every day, and that ingesting too much or too little copper can lead to illness.
At the tap, the problem is corrosion. EPA’s archived consumer factsheet says all water is corrosive toward copper to some degree, and that corrosivity is greatest in very acidic water. The catch for homeowners is that copper contamination generally comes from household pipes. Because of that, EPA says the water system cannot directly detect or remove it. Your utility can follow every rule while your kitchen faucet tells a different story.
Step by step: checking your own water
ATSDR lists the signs of copper contamination as water that is metallic or bitter in taste or smell and/or green-blue in color. ATSDR’s toxicological profile describes the tint as a light blue or blue-green color. Stains around fixtures are a reason to keep checking, not a diagnosis.
ATSDR flags one combination in particular: copper pipes and acidic water, especially in newer or recently renovated homes. Faucets matter too. ATSDR calls water first drawn in the morning after sitting in copper piping and brass faucets overnight the greatest potential source of exposure.
CDC advises flushing faucets that haven’t been used for 6 or more hours by running the water for at least 15 seconds. ATSDR suggests at least 15–30 seconds. Go with the longer time, since it only costs you a few extra seconds. Use the cold tap for drinking and cooking: CDC says to avoid hot water taps because hot water dissolves copper more easily than cold water.
ATSDR notes that tests are available to check if your water is acidic or if copper levels in your water are high. Test for both. The copper result tells you whether there’s a problem, and the acidity result helps explain why. To put your number in context, EPA’s action level for copper is 1.3 ppm, and EPA’s archived factsheet sets the health goal (MCLG) at the same 1.3 ppm.
Don’t confuse your utility’s compliance with your own result. Under the Lead and Copper Rule, utilities test at customer taps. They only have to take extra steps to control corrosion if copper exceeds 1.3 ppm in more than 10% of customer taps sampled. That measures the whole system, so it can’t vouch for your particular faucet.
ATSDR says regularly cleaning or flushing out your system can help keep copper from building up in your water.
What too much copper does, and who should be careful
The health effects depend on how much copper you take in and for how long:
| Exposure | What the agencies describe |
|---|---|
| High amount, usually in water | Vomiting, nausea, abdominal pain, diarrhea |
| Above-recommended amounts over time | Kidney and liver damage |
| Breathing dusts, sprays, crystals | Nose/throat irritation, dizziness, headaches |
| Water above the action level for years | Possible liver or kidney damage |
Copper is essential to the development of babies and children and is found in breast milk. ATSDR expects children to have symptoms similar to adults when exposed to high levels. People with a disorder that causes copper to build up in the body, like Wilson’s disease, may be especially vulnerable. EPA’s factsheet tells them to consult their health care provider.
On cancer, ATSDR says the U.S. Department of Health and Human Services (DHHS), EPA and the International Agency for Research on Cancer (IARC) have each not evaluated the carcinogenicity (whether it causes cancer) of copper.
Medical tests are worth understanding before you ask for one. ATSDR says there are tests to measure the amount of copper in your blood, urine, nails, and hair, and that your medical provider can help decide if a test is needed. High levels can show that you have been exposed to a lot of copper or that your body has a problem regulating it, but these tests will not predict if you will have health problems. They are not part of standard health tests that are done at your doctor’s office and are done through a special lab. Our guide to reading a heavy metals test covers what blood, urine and hair results can and can’t tell you. If your doctor finds substantial exposure, ATSDR suggests asking whether your children might also have been exposed.
Copper sources outside the tap
Pond owners should pay attention here. Blue copper sulfate crystals, used to control algae, have been accidentally ingested by people who confused them for candy or toys. ATSDR advises storing copper powders, crystals, or dusts away from children, pets, or other adults.
If you take a supplement with copper, ATSDR says to monitor your copper intake and talk to your doctor, nurse, or clinic about the right amount. If you work with copper, ATSDR advises to wear the necessary protective clothing and equipment, and always follow safety procedures, and to shower and change your clothes before going home each day.
The bottom line
Copper has been regulated for a long time. Congress passed the Safe Drinking Water Act in 1974. EPA published the Lead and Copper Rule in 1991, and the copper regulation became effective in 1992. Those rules judge the water system as a whole, so checking your own faucet is up to you. Flush, use cold water, test for both acidity and copper, and if you think you have been exposed to high levels, ATSDR says to talk to your doctor, nurse, or clinic, or call poison control.
Copper and lead are separate tests. For lead, see our guide to testing for lead in tap water.
Sources
- cdc.gov – “Chemicals That Can Contaminate Tap Water | Drinking Water | CDC” (2025)
- epa.gov – “Lead and Copper Rule | US EPA” (updated 2026)
- atsdr.cdc.gov – “Toxicological Profile for Copper”
- atsdr.cdc.gov – “Public Health Statement: Copper” (2004)
- archive.epa.gov – “Archived Consumer Factsheet on Copper”
- atsdr.cdc.gov – “ToxFAQs for Copper” (2024)