Calcutta, Sept. 11 : Calcutta, Sept. 11: The civic health department has decided to write to Calcutta Police commissioner Sujay Chakraborty and DC (headquarters) Banibrata Basu to check the quality of drinking water served to prisoners in the central lock-up of Lalbazar. The civic body feels the quality of water is not up to the mark. Member, mayor-in-council (health), Javed Ahmed Khan, said the civic health department has also police permission to collect samples of water from the central lock up. The dispute over water arose after CMC chairman Anil Mukherjee and Khan courted arrest last week in connection with Trinamul Congress law-violation to protest the law and order situation. They were taken to the central lock-up after arrest and detained for more than five hours. When Anil Mukherjee was thirsty, the police gave him a glass of unclean water. It tasted different too. Mukherjee was told by the officer on duty that it was the water they themselves drink and serve to prisoners.