A long-held belief that water stored in a copper jug becomes clean enough to drink has been examined by a chemistry teacher in Kyiv, who says the metal does have a mild disinfecting effect but cannot replace a real water filter.
Serhii Prymachenko, a chemistry teacher of the highest qualification category and senior teacher at Lyceum No. 286 in Kyiv, told the Ukrainian news outlet UNIAN that copper has weakly expressed antibacterial properties. Its ions can damage bacterial membranes, he said, but that antibacterial action is not the same thing as water purification. Leaving tap water to sit in a copper jug will not make it crystal clean, he said, though drinking water that has been in contact with a copper spoon is not harmful either, even if the benefit is minor.
Does Copper Actually Purify Water?
Prymachenko said copper was historically used in households not as a purifier but as a strong, safe and practical material. In the hot, humid climate of South Asia, water spoiled extremely quickly and became a breeding ground for bacteria, he said, which is why copper vessels became a natural health tool as far back as the ancient civilisations of the Indus Valley.
He said the practice became known in traditional Ayurvedic medicine as Tamra Jal, meaning water kept in a copper vessel, and was used as a daily ritual to disinfect water and support digestion long before humanity discovered the existence of bacteria and antibiotics. Owning copper vessels was seen as something exotic in Ukraine, he added.
How Copper Water Bottles Work: Benefits and Limits
Copper cannot substitute for a filter in everyday use, Prymachenko said. Copper vessels or individual copper components cannot remove mechanical impurities such as sand, rust, suspended particles or complex organic pollutants from water. Only a full cartridge filter can do that job, he said.
Even so, he said the scientific community has confirmed that copper vessels can clear water of some harmful bacteria and microorganisms. When clean water sits in a copper container, the metal releases microscopic doses of copper ions, known as the oligodynamic effect, which break down the cell membranes of disease-causing microbes. For surface-level cleaning of liquid, he said, a copper bottle or jug is an acceptable option.
He said the effectiveness depends on how much of the water's surface touches the copper. A copper jug has the largest contact area and the most noticeable effect, a copper bottle is a convenient format with a middling result, and a copper spoon or coin has minimal contact area and an almost symbolic effect.
Genuine copper has a distinctive reddish-pink colour, does not react to a magnet, and develops a green patina over time from chloride and nitrate salts present in industrial air, he said. Quality copper items are usually marked Pure Copper, Cu 99% or Food Grade Copper.
How to Purify Water at Home Without Copper
Prymachenko also explained which folk methods work best when no filter is available, noting that chemists never rely on a single method but combine substances and processes that work together. He said water can be made clean at home or in the field by following steps in order: boiling the water to kill active forms of bacteria, letting it settle for several hours so solid particles sink and any chlorine evaporates, then filtering it through cloth to remove remaining mechanical impurities.
For chemical purification, he recommended using activated or wood charcoal. At the final filtering stage, the charcoal should be broken into pieces the size of a bean, wrapped in several layers of cloth or gauze, and water passed through it slowly. If no cloth is available, the crushed charcoal can be added directly to the water, using 10 to 15 tablets or two tablespoons of campfire wood charcoal per litre, left for 30 to 60 minutes, and the clear water carefully poured off without the sediment. He stressed that barbecue briquettes containing chemical firelighters should never be used for this.
He also described a homemade layered filter made from a plastic bottle, calling it a field option for cleaning very murky water. The method involves cutting off the bottle's base, making a hole in the cap or replacing it with a piece of cloth, then turning the bottle neck-down and layering, from bottom to top: cotton wool, cloth or moss at the neck to hold the contents in; a 3 to 5 centimetre layer of crushed charcoal to remove chemicals and odours; a 5 to 7 centimetre layer of fine clean sand to trap small dirt; and a 3 to 5 centimetre layer of fine gravel or pebbles to catch larger debris and twigs.
Prymachenko said that after any mechanical or charcoal filtration, the water must still be boiled for at least one to three minutes to guarantee the destruction of bacteria and helminth eggs. To inactivate viruses, including hepatitis A, and destroy bacterial spores, he said the water should be boiled for 10 minutes.
Prymachenko has 20 years of teaching experience. He began his career in 2005 after graduating from the National Pedagogical Dragomanov University, later deepening his scientific knowledge through postgraduate study at the National University of Life and Environmental Sciences of Ukraine, specialising in inorganic chemistry. He spent 19 years teaching chemistry and technology courses at the National Aviation University before moving into school teaching.
