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the most environmentally friendly protection against leigonella and other water-borne bacteria


Copper is known as the world’s oldest metal, suitable for crafting weapons, tools, art and other ornaments.

An Ancient Egyptian medical text, the Smith Papyrus (c. 2400 BC), mentions the use copper as a sterilization agent for drinking water and wounds.

The Ebers Papyrus (c. 1500 BC) mentions the use of copper for headaches, “trembling of the limbs,” burns, and itching.

Hippocrates (c. 400 BC) wrote of copper as a treatment for leg ulcers associated from varicose veins. The Greeks also sprinkled a powder of copper oxide and copper sulfate on open wounds and treated wounds with a mixture of honey and red copper oxide.

The Romans (23 to 79 A.D.) described a number of remedies involving copper. Black copper oxide with honey was used to kill intestinal worms and purge the stomach.

In diluted form, nose drops were used to ‘clear the head’. Eardrops relieved ear discomfort and infection, and taken by mouth to relieve mouth sores and ulcers.

The ancient Aztec civilization also used copper for medical purposes, including gargling with a copper mixture for sore throats.

In ancient India and Persia, copper was used to treat lung diseases.

Copper compounds such as malachite and copper oxide were used on boils and other skin conditions. Nomadic Mongolian tribes used copper sulfate, taken by mouth, to treat venereal ulcers.

Throughout history, healers have understood the value of copper in obtaining and maintaining optimum health. Copper based algaecides have long been used by water treatment biologists to safely control algae problems.

Sheffield Plate

In 1743, a layered combination of silver and copper was accidentally invented by Thomas Boulsover, of Sheffield’s Cutlers Company.

While trying to repair the handle of a customer’s decorative knife, he over-heated it too and the silver started to melt.

When Boulsover examined the damaged handle, he noticed that the silver and copper had fused together.


Have you ever wondered:

  • where the expression ‘born with a silver spoon in your mouth’ came from?
  • why people throw silver coins into a fountain or rivers and hope it brings them luck?
  • why, historically, royal families drank from silver goblets and ate with silver cutlery?

It is because, for thousands of years, silver has been know to have anti-bacterial properties.

The amazing thing is how much they knew then – and, of course, how little we know now.

Although, actually, we know more than you might think, particularly in the field of health and safety in public buildings – where clinical trials have shown copper-silver ionisation to be effective in killing legionella and other deadly water-borne bacteria.

First, let’s start at the beginning.

The first major sources of mined silver were around Anatolia in the area of modern day Turkey. The Chaldeans were the first culture to extract silver from other ores around 2500 BC.

The writings of Herodotus, the Greek philosopher and historian, offer some insights to the use of silver as a healing agent.

Known as the ‘Father of History’, Herodotus chronicled the fall of Babylon and revealed that no Persian king would travel without a long train of four-wheeled mule wagons carrying silver jars. This would keep the water fresh for years during the long campaigns.

Recognising the value of silver vessels in water purification and storage, Greek craftsmen produced silver vessels for use on ships and for trade with other countries. The Greek physician, Hippocrates, wrote that silver could prevent disease.

The Ancient Romans would keep silver coins in drinking vessels and other household items.
Chinese emperors and their courts are known to have eaten with silver chopsticks.

Settlers in the Australian outback suspend silverware in their water tanks to retard spoilage.

In the European Middle Ages, particularly during the plague, families of means gave their children silver spoons to suck on. Thus the saying ‘born with a silver spoon in their mouth’ actually means ‘healthy’ rather than ‘rich’.

Early explorers dropped silver coins in wells and water barrels to keep water clean and usable.
Settlers in the American West used silver dollars in jugs of milk to keep it from spoiling. 

Prior to the introduction of antibiotics, Colloidal Silver was used widely in hospitals as a bactericide. By the early part of the 1900s, the use of silver as an antibacterial substance was becoming widespread.

Silver leaf was used to combat infection in wounds sustained by troops during World War I.

In The Lancet (issue 16 February 1918), T. H. Anderson Wells reported that a preparation of colloidal silver was “used intravenously without any irritation of the kidneys and with no pigmentation of the skin.’ 

By 1940, approximately four dozen different silver compounds were being used to treat every known infectious disease. They were available in oral, injectable, and topical forms.

Subsequent experiments showed that the two metals behaved as one when he tried to reshape them, even though he could clearly see two different layers.

History of Ionisation

Copper-silver ionization was perfected in the 1960s by NASA as a method of purifying recycled water supplies aboard space craft.

This method of water purification without the use of chlorine, has been developed in further space programs as well as major airlines.

Ionisation is now used in ocean going vessels, luxury yachts, off-shore drilling rigs, breweries, bottlers and many other water systems.

Since the 1980s commercial, industrial and medical applications have exploited the unique characteristics of copper-silver ionisation.

And ever since launch in 1981, Tarn-Pure has been at the cutting edge of all the major developments in this extraordinary technology.

The biocidal effect of combined silver and copper ions were first researched by Professor Charles Gerba at Arizona State University. Systems consisted of stabilised DC power supplies feeding power to silver/copper alloy electrodes placed in water circuits. They were fitted to swimming pools, cooling towers also hot and cold water systems.

In medicine, Professor Victor Yu at the University of Pittsburgh tested silver copper ionisation as a legionella control biocide in sixteen hospitals, which have been legionella-free since 1995. To read more about this study please click here.

The seminal justification for copper-silver ionisation is Dr Janet Stout’s ASHRAE 2007 study which compared silver copper ionisation with three other permitted Legionella biocide methods (chemical, thermal and ultra violet) and concluded:

‘Each of the these methods has completed some of the evaluation criteria but only copper-silver ionisation fulfilled all criteria’.

Following evaluations in the UK, the Health & Safety Commission approved the process for hot and cold water systems to control outbreaks of Legionnaires Disease.

Ionisation has been approved for use within the NHS as specified in the Health and Safety Executive directive ACoP L8: ‘Legionnaires’ disease. The control of legionella bacteria in water systems.’


Since 1981, Tarn-Pure has both led and followed all of these developments in copper-silver ionisation. Initial applications were in swimming pools.

In 1985, following the death of twenty-two patients at Stafford District General Hospital, Tarn-Pure began to exploit the efficacy of copper-silver ionisation as a biocide against legionella and other water-borne bacteria.

Since then, Tarn-Pure’s technical development team has always been at the forefront of the application of this extraordinary vital, natural technology.

Tarn-Pure equipment has been chosen by research scientists all over the world as the standard for further research studies.

To this day, Tarn-Pure continues to make a major contribution to controlling surface infection in hospital wards, food preparation facilities, the laundry, toilets and bathrooms, acting as a supplementary biocide to normal cleaning procedures.

Please contact us for further information on what the Tarn-Pure copper-silver ionisation systems can do for you.

If you are a Duty Officer or Responsible Person and have not considered Tarn-Pure and the effectiveness of copper-silver ionisation, please contact us.