Drinking water from copper: what the evidence says and how to use it

In the 2012 study, researchers added diarrhoea-causing bacteria to water and stored it in copper pots at room temperature. After 16 hours, no bacteria could be recovered.

The dissolved copper measured about 0.18 mg/L. The WHO guideline value for copper in drinking water is 2 mg/L.

That supports copper as a traditional way to store water. It does not show that copper water prevents or cures any illness.

Ayurveda traditionally recommends water stored in copper (tamra jal). That is a traditional practice, not clinical evidence.

• Before first use, wash the inside with mild soap, then rinse with lemon and salt and with water.
• Fill it with plain drinking water at room temperature.
• The usual practice is to fill it at night and drink it the next day.
• Empty and refill it daily; don't top up yesterday's water.
• Keep the cap off and let it dry upside down once a week.

• Hot water, tea or coffee: heat raises the copper that dissolves.
• Lemon water, juice, buttermilk or anything sour: acid does the same. The US FDA Food Code bars copper from food below pH 6.
• Milk, sweet drinks and fizzy drinks.

No health authority sets a daily amount of copper-stored water. Too much copper upsets the stomach, which is why drinking-water limits exist.

Treat copper water as part of your daily water, not all of it. For children, pregnancy or a medical condition, ask your doctor.

A dark brown or black film inside is copper reacting with air and water. It is normal, and it is not a sign of fake copper.

Clean the inside every week or two. Shake it with lemon juice and salt, or vinegar and salt, then rinse well and dry with the cap off.

A green layer (verdigris) is different: it forms with moisture or acid. Clean it off completely before the vessel holds water again.

• Capacity in millilitres, not just “1 L”. Marketplace buyers often complain a 1-litre bottle holds 930–950 ml.
• Wall thickness: a bottle that dents when squeezed is thin sheet.
• The cap thread and seal: fill it, close it, and hold it upside down.
• Joints: a one-piece or well-brazed body leaks less.
• Any lacquer or print should be on the outside only. The inside should be bare copper.
• For gifting and corporate orders, ask about boxes and branding with your enquiry.