The trio carry adulterated diesel in a jerrycan on Andul Road. Picture by Sanat Kumar Sinha

Outside Indian Oil’s depot at Maurigram a tanker driver is woken up from the siesta he’s been taking to kill time before he can enter for a fill. We tell him we want to buy oil, he says: “Go to a petrol pump.”

But we want it cheap. The tall man in a half-sleeve shirt with a gamchha round his neck is reluctant to speak.

“Kitna diesel chahiye aapko (How much diesel do you want)?” he asks after much cajoling.

It’s around 11.30 in the morning. Tankers are lined up on both sides of narrow Andul Road that leads to the depot, less than 50km from Calcutta. Dotted with teashops, eating places, garages, the area is buzzing with people going about their work or chatting.

The driver points to a person standing at a teashop just outside the depot and we walk up to the stocky, dark man of about 5ft5in in black trousers and a cream, half-sleeve shirt with the top two buttons open.

We are not introduced. The driver simply says in Hindi, “This man wants 50-100 litres every month.” The man glances at us, looks at the driver and mumbles, “Hoye jaabe (it’ll be done)", paying us the attention an inconsequential client deserves.

We move away with the driver for a cup of tea and chat about how one can transport the oil from there. He is sensing a business opportunity and talks freely.

“I know people who can provide you with any amount above 20 litres. You will get a lower rate than at the petrol pump,” he says. He stands to earn a commission as the go-between.

“(But) If you want a really huge quantity, you will have to speak to Dilipda. He has a stronghold on the union. He can provide up to one tanker at a time,” the driver says before hauling his tanker inside the depot.

Oil tankers parked in a garage in Maurigram, in Howrah, where diesel is siphoned off, adulterated and sold cheap. The garage is around a kilometre from the Indian Oil depot. Picture by Sanat Kumar Sinha

“Dilipda” is not the leader of the any of the unions inside the Maurigram depot. He rules from outside.

Indian Oil denies suggestions that oil is smuggled out from inside its depot or even that it is taken out from tankers once they come out after filling up.

A spokesman says: “The allegation is baseless. The Indian Oil terminals at Maurigram and Budge Budge have the most modern facilities that are fully automated. We haven’t received any complaint.”

Dilipda’s name crops up in another context. A petrol pump owner has bought up to half a tank of diesel through him.

We part ways with the tanker driver after setting up another meeting in two-three days, wiser in the knowledge that oil can be bought unofficially at a lower than market rate.

At least 150,000 litres of adulterated oil, or katatel, is sold in Calcutta alone to autorickshaws every day by a rough estimate. At about Rs 35 per litre, that makes it a daily business of Rs 52.5 lakh, or over Rs 190 crore a year. It is an extremely conservative estimate, but still explains why the authorities will do nothing to stop it.

Where are the ingredients of this oil — a mix of petrol and kerosene or petrol, kerosene and naphtha – coming from?

(With inputs from Sambit Saha)