Officials say 30 percent of Pakistan city’s water supply is wasted or stolen, worsening an already chronic shortage.

For years armed gangs have controlled part of the water supply in Pakistan’s largest city of Karachi.

The so-called water mafia have stolen millions of dollars worth of water and sold it on the black market.

On the outskirts of the city, hidden in plain view, illegal water stations operate tapping into underground pipelines owned by the state, and in some cases sewage wells.

All day trucks fill up with stolen water, and sell it all over Karachi at an inflated price, denying poor residents much needed water.

Water traders with 30 to 40 tankers reportedly earn as much as $16,000 a day.

According to the city’s water board, Karachi only has enough water to meet 50 percent of its needs, and around 30 percent of the water is wasted or stolen.

Of the total amount of water stolen, over 70 percent is reportedly sold to big business.

Authorities in the city, the country’s financial capital, are trying to crack down on the practice, carrying out raids on 200 pumping stations.

Despite the crackdown, the leaders of this “underwater world” are still operating and the cost of illegal water in Karachi has now doubled.

One businessman who buys water from illegal dealers said powerful and well-connected individuals are to blame for the continued illegal practice.

“They are holding us by the necks basically and this is all because a few big people are involved in this and who are the caretakers and who are the people who are making money,” he said. “There are people on higher levels involved.”

Al Jazeera’s Nicole Johnston reports from Karachi.