Residents of the city may have benefited from better access to groundwater, but it has also given rise to the threat of arsenic poisoning. A study conducted by the Central Ground Water Board confirmed presence of arsenic above the prescribed Bureau of Indian Standards (BIS) desirable limit (0.01mg/litre) in water samples collected from 10 out of 11 localities of the city. The parameter complies with limit set by the World Health Organisation. The study titled `Occurrence and distribution of Arsenic in ground water and surface water of Lucknow city' has revealed presence of arsenic even in samples of water from Gomti river, which is one of the vital sources of Lucknow's drinking water. Most of Lucknow, especially the trans-Gomti area, is supplied by water from tubewells by the Jal Sansthan or through private bore-wells while in the Old city , the supply is primarily from the river. Certain areas also get water through handpumps. The areas affected (in descending order) include Gomtinagar ­ 0.030 mg/litre, Vijaynagar ­ 0.023, Behsabagh ­ 0.022, Aliganj (handpump) ­ 0.020, LIC Hospital ­ 0.019, Transport Nagar ­ 0.018, Sujanpura ­ 0.017, Ashiyana Colony ­ 0.016, LDA Colony ­ 0.015 and Lucknow Zoo (shallow tubewell) ­ 0.010. Arsenic presence was found safe (below 0.01 mg/ litre) only in water samples from Murlinagar, Udaiganj and Regiment Bazar (handpump) of Cantt Road area.