To use a copper cup for drinking water, pour in plain, room-temperature water and drink it, or cover the cup and let the water rest for about 6–8 hours (overnight) if you want traditional copper water, or tamra jal. Most people drink one or two cups of copper-stored water in the morning and the rest of their water from any clean vessel. Keep the cup for plain water only, never acidic or hot drinks, and clean it every 1–2 weeks.
This guide covers how long to leave water in a copper cup, how often to drink from it, what a copper drinking cup is (and is not) good for, how to clean it, and where the popular story about hospitals and copper cups comes from.
What Is a Copper Cup for Drinking Water?
A copper drinking cup, sometimes called a copper glass or tumbler, is a simple open cup made of copper. In Indian homes it is usually paired with a larger copper vessel: water is stored overnight in a jug, pitcher or bottle and poured into copper cups in the morning.
Our copper cups come as part of the Copper Pitcher Set, with either 2 or 4 cups. Each cup holds 0.35 litres (12 oz), and the 1.5 litre (50.7 oz) pitcher fills several of them. Like the pitcher, the cups are made from a single sheet of lab-tested 99%+ pure copper, lacquered on the outside to protect the surface and left natural inside, so the water touches copper.
A copper cup for water is not the same as a Moscow mule mug. Many cocktail mugs are lined with nickel or stainless steel inside because they are meant for acidic drinks. A water cup should be unlined. If you are unsure what you own, see copper mugs vs copper-plated mugs.
How Long to Leave Water in a Copper Cup
It depends on what you want from it:
- Just drinking: no wait is needed. Pour water and drink it as you would from any cup.
- Traditional copper water: the custom is to let water rest in copper for about 6–8 hours, which is why it is usually done overnight. Cover the cup with a saucer or lid so dust and insects stay out.
- Not longer than about a day: there is no benefit to leaving water standing for days. Empty, rinse and refill.
Because a cup is small and open, many people find it easier to store the water overnight in a covered pitcher or bottle and use the cup only for drinking. Either way works. If you want to know what changes in the water during those hours, read what happens to water after 8 hours in copper.
How Often Should You Drink From a Copper Cup?
There is no official number of copper cups per day. The traditional practice is a glass or two of copper-stored water in the morning, with the rest of the day's water from any clean source. That is a sensible pattern to follow.
Some useful context on amounts:
| Reference point | Value |
|---|---|
| Adult recommended daily intake of copper (all sources, mostly food) | 0.9 mg per day |
| Adult tolerable upper limit | 10 mg per day |
| World Health Organization guideline for copper in drinking water | 2 mg per litre |
| Copper measured in water after 16 hours in a copper vessel (Sudha et al., 2012) | 0.177 mg per litre |
In that study, water kept in copper picked up only a small amount of copper, well under the WHO guideline. Much of your copper still comes from food, so copper water is best treated as one small part of your day rather than your only drinking water. For a fuller answer, see how much copper water to drink in a day. If you have a condition that affects how your body handles copper, such as Wilson's disease, check with your doctor first.
How to Use a Copper Glass for Drinking Water: Step by Step
- First use: wash the cup with mild dish soap and water, rinse and dry.
- Fill with plain water: clean, room-temperature drinking water only.
- Rest (optional): for traditional copper water, cover and leave it overnight, about 6–8 hours. Or pour from a copper pitcher or bottle where the water has already rested.
- Drink in the morning: most people have one or two cups on waking.
- Rinse and dry: rinse after use and let the cup dry fully before storing it upside down.
For the full morning routine, see our guide to the copper water routine.
What Not to Drink From a Copper Cup
- Acidic drinks: lemon water, juice, soda, kombucha, wine or anything with vinegar. Acids react with copper and can draw much more copper into the drink.
- Hot drinks: tea, coffee or hot water. Heat speeds up the reaction too.
- Milk and sweet drinks: they are hard to clean out and can react with the metal.
Our product pages say it plainly: plain water only. More detail is in why to avoid acidic substances in copper.
Why Is My Copper Cup Turning Dark?
The inside of an unlined copper cup starts to darken from its first contact with water. This is normal oxidation, called patina, and it is how genuine copper behaves. Within a few weeks the inside settles into an even, antique colour. You can leave it, or bring back the shine whenever you like.
How to clean a copper cup
- Every day: rinse with water, or hand wash with regular dish soap.
- Every 1–2 weeks: rub the inside with lemon and salt, or vinegar and salt. For a deeper clean, the method on our pitcher set page is ¼ cup of white vinegar plus 1 teaspoon of salt, topped up with water and left for 30 minutes.
- Rinse thoroughly, wash with soap, and dry completely.
Green spots usually mean the cup was left wet too long; clean it the same way and dry it fully. Do not use a dishwasher, steel wool or harsh chemical cleaners. The same steps work for bottles: how to clean a copper water bottle.
Did Hospitals Use Copper Cups?
A story often shared online says hospitals once gave patients copper cups and later switched to plastic. We have not found good records showing that copper drinking cups were ever standard in hospitals, so we treat that story with caution.
What is documented is newer research on copper as a surface material. Laboratory and hospital studies have measured fewer bacteria on copper-alloy surfaces such as bed rails and door handles than on standard materials, and the U.S. Environmental Protection Agency has registered certain copper alloys as antimicrobial surfaces. We cover this in why hospitals are using copper surfaces. These findings are about copper surfaces and stored water; they do not mean that drinking from a copper cup treats or prevents any illness, and we don't claim it does.
Cup, Pitcher or Bottle?
A copper cup works best alongside a larger vessel. A pitcher with cups suits the home and sharing water at the table; a copper water bottle suits carrying water through the day. Our bottle is handmade from a single circle of 21-gauge pure copper, with no joints or seams, hand-hammered at least 1,200 times and fitted with a leak-proof cap. If you want both, our two-bottle set comes with two 12 oz copper cups. You can compare everything in our copper water vessels collection.
Kaarigar is not a reseller. We have made our own copper products in our workshop in India since 2013, control copper quality in-house, and pay our artisans up to 50% more than typical industry rates.
Copper Cup FAQ
How long should I leave water in a copper cup before drinking?
For traditional copper water, about 6–8 hours, usually overnight with the cup covered. If you are simply drinking water, there is no need to wait.
How often should you drink from a copper cup?
A common pattern is one or two cups of copper-stored water in the morning, with the rest of your water from any clean vessel. There is no benefit to drinking only from copper.
Can I drink hot water or tea from a copper cup?
No. Use a copper drinking cup for plain, room-temperature or cool water only. Heat and acidic drinks increase how much copper moves into the drink.
Can I put ice in a copper cup?
Yes, ice in plain water is fine. Avoid acidic drinks, cold or not.
Is the dark colour inside my copper cup safe?
The dark layer is patina, a natural form of copper oxidation, and it shows the inside is real, uncoated copper. Clean it with lemon or vinegar and salt whenever you want the shine back, then rinse and dry well.