The Left Front board of the Calcutta Municipal Corporation (CMC) is examining the Ahmedabad model for imposition of water charges on residential consumers. The model does not link water charge with property tax.

Once it is implemented, even those exempt from paying property tax will have to cough up the water fee if they consume filtered water supplied by the civic body.

The earlier civic board, run by the Trinamul-BJP combine, had imposed water tax on owners of properties with an annual valuation of Rs 5,000 or more.

Around 1.39 lakh house-owners were brought within the tax purview.

The authorities, however, had to withdraw the tax on pressure from Trinamul supremo Mamata Banerjee, who held that the policy allowed ?unfair exemption? to a large number of well-off house-owners in certain pockets.

Mayor Bikash Ranjan Bhattacharyya, too, said: ?I don?t believe that a house-owner who pays more property tax uses more water.?

In Ahmedabad, he added, the owners of houses with annual valuation up to Rs 500 have been exempted from paying property tax after being brought within the purview of the water fee and drainage and sewerage charges. ?We are exploring whether a similar system can be implemented in Calcutta.?

The mayor has directed municipal commissioner Alapan Bandyopadhyay to work out water charges for residential buildings, keeping in mind the interests of the lower income groups.

The state government has set the lowest rate for water charge at Rs 15 per month. The civic authorities are thinking of further downsizing the lowest rate.

The CMC does not levy drainage charges on residential buildings, though there is a law empowering the civic authorities to do so.

There are around three lakh households in the city that are supplied filtered water by the civic body. Before the earlier board imposed water charges, only house-owners with large ferrule (20 mm and 25 mm) connections had to pay water tax.

Around 40,000 households then paid the tax.

In Calcutta, owners of houses with an annual valuation less than Rs 300 are exempted from paying property tax. The lowest slab of taxable annual valuation is Rs 300-600.