Unlined copper is generally fine for drinking plain water for a short time, because drinking water is usually not acidic. It is not safe for acidic food and drinks such as tomato sauce, vinegar, lemon, fruit juice, yogurt, wine or cocktails, and food should not be left standing in it: acid dissolves copper into what you eat or drink, and too much copper can cause copper poisoning. That is why copper cookware, and copper mugs used for acidic drinks, are lined with tin.
When does copper become harmful?
Copper is an essential mineral. According to the US National Institutes of Health, adults need 900 micrograms a day, and the upper limit from food, drinks and supplements combined is 10 milligrams a day (NIH copper fact sheet). The question is how much copper moves from the vessel into what you consume. Acidity, contact time and the condition of the surface decide that:
| Use | Risk | Why |
|---|---|---|
| Tomato sauce, vinegar, lemon, yogurt, pickles or wine in unlined copper | High | Acid dissolves copper; longer cooking and storage increase it |
| Moscow mule or other acidic cocktails in an unlined copper mug | High | Lime juice and mixers are acidic |
| Food left in unlined copper for hours or overnight | High | Long contact time |
| Pan or pot with worn tin showing copper underneath | Medium to high | Food touches exposed copper |
| Plain water from an unlined copper cup, drunk straight away | Low | Drinking water is usually not acidic; short contact |
| Tin-lined copper cookware with an intact lining | Low | Food touches tin, not copper |
Section 4-101.14 of the US FDA Food Code bans copper and brass from direct contact with food and drinks below pH 6, naming vinegar, fruit juice and wine as examples.
Is it safe to drink water from a copper cup or water bottle?
Our copper pitchers and water bottles are tin-lined, so they are safe for any drink
The US Environmental Protection Agency recommends a pH of 6.5 to 8.5 for drinking water, which sits above the FDA's acid limit. So drinking plain water from an unlined copper cup is low risk compared with acidic drinks. A few rules matter, especially with copper water bottles that hold water for hours:
- Fill it with plain water only: no lemon water, juice, sparkling water, sports drinks or tea.
- Do not leave water standing in it for long periods.
- Wash and dry it after use; clean off any green marks inside before drinking from it again.
- Claims that copper-stored water has special health benefits are not something we make.
For cocktails and acidic drinks, choose a tin-lined copper mug. Our range is in copper cups and mugs.
Can you cook in unlined copper?
Not with acidic food, and not for storing food. Unlined copper bowls and pans have specialist uses, but everyday copper cookware is lined. A tin lining does not take away copper's fast, even heat; it only puts a thin barrier between food and copper. That is why traditional Turkish copper pots, pans and egg pans are always tin-lined inside. See our tin-lined copper pans and skillets.
Is tin-lined copper safe? Is tin lining toxic?
Pure tin used for lining cookware has low toxicity. The US Agency for Toxic Substances and Disease Registry (ATSDR) notes that metallic tin is not very toxic because it is poorly absorbed by the gut; only large amounts of inorganic tin compounds cause stomachache, anaemia and liver or kidney problems. Two things matter with a tin lining:
- Purity: the lining should be lead-free pure tin. Our workshop uses lead-free pure tin.
- Condition: when the tin wears through and copper shows, the piece needs re-tinning.
Tin melts at about 232 °C (450 °F), so never heat a tin-lined pan empty. We explain re-tinning in how to tin copper.
Our workshop also re-tins old copper. Copper cookware bought from modabakir.com is re-tinned free of charge one year after purchase; just email destek@modabakir.com with your order number.
Copper poisoning symptoms
According to the NIH, too much copper can cause abdominal pain, cramps, nausea, diarrhoea and vomiting, and getting too much regularly can damage the liver. How quickly symptoms appear depends on the amount and the person. If you have severe vomiting, abdominal pain or confusion, seek medical help straight away.
Is green copper dangerous?
The green patina that forms on the outside of copper is a reaction with air and moisture and does not reach your food while it stays on the outside. Green marks inside a cup, pot or pan that touches food are different: they show exposed copper reacting. Clean the surface and check the lining before using it again. For cookware safety in more depth, see are copper pans safe.
What to check when buying copper for food or drink
- Solid copper or copper-plated?
- Is the surface that touches food tin-lined, and is the tin lead-free?
- Sheet thickness in mm and weight in grams.
- Made for cooking and drinking, or for decoration?
- Does the maker have its own workshop and put material details in writing?
Frequently asked questions
Is unlined copper safe?
For plain water drunk straight away, the risk is low. For acidic food and drinks, or for storing food, unlined copper is not safe because acid dissolves copper into what you consume.
Is it safe to drink water from a copper bottle every day?
Plain water drunk without long standing is low risk. Do not keep water in the bottle for many hours, and never fill it with lemon water, juice or sparkling water.
Are unlined copper mugs safe for Moscow mules?
No. A Moscow mule contains lime juice and is acidic; the FDA Food Code bans copper contact with drinks below pH 6. Use a tin-lined copper mug.
Is tin-lined copper cookware safe?
Yes, as long as the lining is lead-free pure tin and intact. Metallic tin is poorly absorbed by the body. Re-tin the piece when copper shows through.
Can you get copper poisoning from copper pots?
Yes, if acidic food is cooked or stored in unlined copper or in pots with worn tin. Tin-lined pots with an intact lining keep food away from the copper.
About this guide
This guide was written in the Moda Bakır workshop in Kahramanmaraş, Turkey, where we have been making copper pots, pans, cups and coffee pots for around 40 years. Our own craftsman tin-lines our cookware, and re-tins old copper, with lead-free pure tin. Health information comes from the institutions named in the text (NIH, FDA, EPA, ATSDR); for personal health questions, ask your doctor.