Handy copper cure

A non-governmental organisation uses the metal to purify water

Published: Thursday 31 March 2005

Handy copper cure

-- Domestic sewage, industrial sludge and agricultural wastes pollute almost all surface water in the country. Filtration and chlorination are often used to clean it up for domestic utilisation. However, most areas in the country lack such facilities and many believe that well water from underground aquifers is a good source of potable water. Almost all rural inhabitations in the country are now provided with water drawn from borewells -- in fact, such water sources cater to a large percentage of domestic requirements even in cities and towns.

However, even borewell water has contamination problems. Recent research by several agencies has shown that microbes contaminate 30 per cent of the borewells in villages and 60 per cent of such wells in towns and cities in Mysore district, Karnataka. Ajay Memorial Drinking Water Foundation(ajmdwf), Mysore was one of the agencies involved in the research. After these studies, this foundation advised people to boil borewell water before consumption. But people in the district rejected ajmdwf's advise as impracticable: they could not afford the extra costs required for boiling the water.

This forced the foundation to search for other alternatives. Copper vessels have been traditionally used to store water; the foundation decided to check if this age-old method could purify water. Copper vessels of various sizes were used to hold water ranging from 0.25 litres (l) to 20 l. There was some success, but the vessels failed to purify large volumes of water within 24 hours.

The researchers did not give up. They decided to use rectangular sheets of domestic grade copper for their experiments. The sheets were dipped into buckets of water. But there was little success: the water could not be purified within 24 hours. Moreover, domestic grade copper had many impurities: it was mixed with toxic metals such as zinc and lead.

The researchers then decided to use the electrolyte variety of copper sheets -- these are used for industrial purposes. Sheets of various sizes were dipped into water-filled buckets. Water quantity was also changed. The experiments began in 2001 and finally in August 2004, there was success. Electrolyte grade copper sheets 61 cm long and 17.5 cm wide was found to purify 10 l water in 24 hours. 41 cm long and 12 cm wide copper sheets purified 5 l of water in a day, while 61 cm long and 35 cm wide sheets cleaned up 20 l of water in the same time.

Take care The copper sheets have to be cleaned initially with a mixture of tamarind and common salt to make it grease and rust free. Once the water has been tested, the sheets can be cleaned with a common dish wash soap. They also require cleaning with tamarind once a week.

Care should also be taken to ensure that the water is purified in food grade stainless steel or polyvinyl chloride containers. Aluminum vessels should be strictly avoided. Borewell waters have high salt content and they form white crusts in the containers. These can be easily removed with a mixture of concentrated acetic acid and hydrochloric acid.

Cheap and advantageous The 61 cm long and 17.5 cm wide sheet costs only Rs 100 and can last for more than 20 years. It is thus a far cheaper option to purify water than conventionally used domestic devices. The commonly used Aqua Guard, for example, costs a few thousands of rupees and requires frequent repairs -- it also consumes expensive electricity. Even boiling water consumes liquid petroleum gas, kerosene or wood worth Rs 300, every year. There are other advantages. The human body requires around 3 microgrammes of copper, every day. The metal forms a key part of the oxygen carrier haemoglobin and protects against iron deficiency. Besides, copper deficiency can cause maladies such as Wilson's disease. But most poor people in India do not obtain copper from their diets. The purifying sheets can serve this purpose.

A Ramalingam is the President of Ajay Memorial Drinking Water Foundation, Mysore, Karnataka

Subscribe to Daily Newsletter :

Comments are moderated and will be published only after the site moderator’s approval. Please use a genuine email ID and provide your name. Selected comments may also be used in the ‘Letters’ section of the Down To Earth print edition.