In the villages near Africa’s biggest copper mine, you can smell and taste the pollution. As a legal battle against metals giant Vedanta/KCM reaches London, villagers in Chingola, Zambia, tell of blighted lives and a looming catastrophe.

You can’t see the old Chingola copper mine, with its smelter and refinery, from the village of Shimulala. It’s miles away, beyond 300ft-high hills of waste tailings, the leach plant, the main pollution control dam and the 1,600ft-deep open pit that is one of Africa’s largest holes.

But you can smell and taste the pollution from the biggest copper mine in Africa. If you pump a glass of water from the borehole outside the little church in Shimulala, you will see it is bright yellow, smells of sulphur and tastes vile.

Mining giant Vedanta’s subsidiary company KCM drilled the borehole in 2010 for the village after the Mushishima stream was turned into a river of acid when mining chemicals spilled into it. But a leaked company letter says that chemists who tested borehole water there in 2011 found it tainted with copper residues, acid and minerals, and said it was unfit for consumption. Now the villagers must use the stream too.

1,800 people from Shimulala, Hippo Pool, Hellen and Kakosa villages took their complaints to the high court in London in a case that could last years and make giant mining companies working in developing countries address local pollution more seriously.

The villagers say acid spills and contaminated water in their streams, rivers and boreholes are getting worse. “The frequency and severity of spills is higher and more consistent. Before we could not smell [the pollution] but now we can. The ground is contaminated, our crop yield has dropped, the maize crop is about half what it was,” said Leo Moulenga of Shimulala. “When there is a spill, the air is very acidic. Last week they spilled a lot. It was awful. In the future we don’t think people will be able to live here. It is becoming uninhabitable. The pollution has been incremental. Now it’s getting worse.”

Floribert Kappa, of Hippo Pool, said: “I used to go to the Kafue river to draw water and started drinking it as normal. I saw that fish had died and were floating on the river. We ate the fish and soon everyone started crying with stomach pains. I was given some medicine, but the pains got worse. I collapsed and was taken to a hospital. The diagnosis was that I had drunk or eaten something acidic which had caused damage to my chest and intestines. I was told the damage was permanent. Now I live on painkillers. Everyone here has been affected in some way. We all use the same water. We have tried chlorinating and boiling the water but it still smells acidic.”

Last year Vedanta/KCM made up to £320m profit from the mine but engineers who have worked there say that its pollution treatment works have been pushed beyond their limits by the company to maximise output.

“The feed in … has been increased to over 50,000 tonnes per day. They were designed to handle 30,000 tonnes,” said one engineer. “Degraded equipment like leaking pumps, pipes, and settling ponds have given to excessive spillages and water overflowing into the Mushishima stream and subsequently the Kafue river. It poses a possible environmental catastrophe. Power failures and deficient pumps frequently result in slurry spills and effluent containing sulphuric acid, lead, zinc, iron and mercury being dumped into rivers.”

The mine has a long history of pollution from its tailing dams, processing plants and old pipes. In 2011, the high court in Lusaka ordered Vedanta/ KCM to pay about £1.3m to 2,000 residents of Chingola after sulphuric acid and other chemicals were discharged into a tributary of the Kafue in 2006.

The judge said Zambians “should not be dehumanised by greed and crude capitalism which put profit above human life. KCM was reckless and had no regard for human, animal and plant life. Chingola residents were guinea pigs.”

Vedanta later appealed to the supreme court, claiming that it was not responsible for the pollution. The verdict was upheld, but the supreme court reduced compensation to people affected by the spillage to virtually nothing.

Much of the infrastructure of the present mine is more than 40 years old. The copper is now worked largely underground but the deep, opencast pit is one of the biggest in Africa – more than four miles long, a mile wide and 1,600ft deep. Mine waste, which is being reworked to extract copper residues, now rises in miles of 300ft hills stretching around the town of Chingola.

Large-scale mining led by global companies listed on the London stock exchange has expanded dramatically in the past decade. Chinese and Indian growth and the rising price of metals has led to the exploitation of new areas of the resource-rich Amazon, India, Indonesia southern Africa and the Philippines. But the boom has been accompanied by evictions, land grabs, human rights violations and damage to water supplies, say development and human rights groups.

Protests against Vedanta will take place in Chingola and Lusaka in Zambia and five Indian cities to coincide with its annual meeting in London.

Vedanta responded, saying: “We have received a letter from Leigh Day [the law firm representing the villagers] making certain allegations about KCM’s mining activities in Zambia.

“We are committed to fully investigating the matters alleged and we have sought further information from Leigh Day and their clients. Once we have completed that investigation we will provide Leigh Day with a full response. Until we have done that, any court proceedings are premature.”