The civic authorities are considering a proposal to realise water charges by regularising illegal ferrules in houses after exempting most of them from paying the charge.

The civic water supply department can earn Rs 30 crore annually by slapping charges on the illegal ferrules. It will meet the annual power bill of the department.

The Calcutta Municipal Corporation (CMC) is planning to install meters on the illegal connections. The charge is likely to be Rs 3 per 1,000 litres. The owner of the house will also have to shell out Rs 150 annually as meter rent.

According to the CMC Act, there should be one ferrule per house. But over 100,000 houses in the city have one or two additional ferrules, said mayor Bikash Ranjan Bhattacharyya.

“Our water distribution system is under strain because of the illegal ferrules. If the house-owners refuse to pay up for the filtered water supplied through the illegal ferrules, the connections will be snapped.”

In the last municipal budget, Bhattacharyya had imposed water charges only on domestic consumers with 20 and 25-millimetre ferrules. A vast majority of houses have 10 and 15-mm ferrules.

Municipal commissioner Alapan Bandyopadhyay said: “An additional ferrule in a house means less water in the neighbour’s house. It cannot be tolerated.” He estimated that over 7 million gallons — produced at a cost of Rs 1.2 lakh — are drawn illegally by Calcuttans every day.

There are 236,000 legal residential connections in the city, said mayoral council member (water supply) Mrinal Kanti Mondol. The councillors turn a blind eye to the illegal connections to prevent loss of votes.

Civic chief engineer (water supply) Bibhas Maity said illegal ferrules are more common in the added areas. “There are even illegal commercial connections on the eastern fringes and Garfa, Ranikuthi, Behala, Jadavpur, Santoshpur, Ekbalpore, Garden Reach and Metiabruz.”