INDIAN J. ENVIRONMENTAL PROTECTION, VOL. 34, NO. 5, MAY 2014 401 © 2014 - Kalpana Corporation Leaching Study for the Microbial Contamination of Groundwater, Delhi Gate, Delhi A. Kumar, L. Nirpen, A. Ranjan, K. Kaur, K. Gulati, S. Thakur and T. Jindal Amity University, Department of Amity Institute of Environmental Toxicology Safety and Management (AIETSM), Noida- 201 303 Delhi, the capital of India is one of the fastest growing and developing city in the world. The rapid growth of Delhi in past decade has significantly increased the loading of municipal and domestic waste in environment. The drains in Delhi are unlined and hence the risk of groundwater contamination increases multifold. Lysimetric experiment was setup for the analysis of physico-chemical and microbial contamination of groundwater through leaching from the saturated zone of soil profile near to drain site. Samples (drain and soil) were collected from the site of Delhi Gate, Delhi. The physico-chemical parameters, like colour, odour, presence of particle, pH, temperature, total dissolved solid (TDS), total suspended particle (TSS), total hardness, alkalinity, biological oxygen demand (BOD) and chemical oxygen demand (COD) of groundwater sample were tested, which indicated the positive physico-chemical and microbial contamination in groundwater leachate and drains sample. Total plate count, total coliform and most probable number test also made to ensure the microbial contamination in groundwater, drain sample, control leachate and drain leachate. The result for microbial contamination were exceeding in most of the sample except groundwater sample from the limit (1.0x10 2 cfu/mL) of WHO standard. Results of the study are posing the serious concern for groundwater through unlined drains and make science-based decisions on the risks associated with groundwater. IJEP 34 (5) : 401-408 (2014) (Received on August 1, 2013) the Yamuna river. The industrial effluent load is 320 MLD. Municipal solid waste generation is estimated to be 5,000 mt/day (MEF, 1997). It is evident that many parts of the industrial area in India are colonized and are in very close vicinity of the industries are using groundwater for drinking, cleaning, bathing, domestical and other agricultural practices. In the close vicinity of this industrial area there is dense population of residents, who gen- erally use undergroundwater for most of their domestic purposes (Siddiqui and Sharma, 2009). Historically, groundwater supplies were thought to be free of pathogenic microbes due to the natural filtering ability of the subsurface environment and the distance a microbe would have to travel in order to reach the ground- water source. Contaminants that find their way into groundwater may originate due to lack of treatment, improper management of waste- KEYWORD Microbes, Coliform, Feacal coliform, Leaching, Industrial effluent. INTRODUCTION Increasing human population has exerted an enormous pressure on the provision of safe drinking water especially in developing countries (Umeh et al ., 2005). Delhi is one of the developing cities in the world which has a great interest for the microbial population in drinking water due to exposure of unrestricted unlined drain/sewage wastewater flow, which may have a major and serious unpredicted problem for the groundwater contamination through the soil profile as well as other sources. In India, Delhi is one of the largest municipal solid waste (MSW) generating city. Sixteen drains are discharging about 1,900 MLD of municipal sewage and wastewater into