Thirteenth International Water Technology Conference, IWTC13 2009, Hurghada, Egypt  NATURAL AND HUMAN IMPACTS ON THE GROUNDWATER UNDER AN EGYPTIAN VILLAGE, CENTRAL NILE DELTA – A CASE STUDY OF MEHALLET MENOUF Zenhom El-Said Salem Geology Department, Faculty of Science, Tanta University, Tanta 31527, Egypt ABSTRACT Due to the new modern life style in the Egyptian villages, a huge amount of water is used in domestic purposes. Because most of the villages are unsewered, the used water is artificially recharged to the subsurface causing water logging and groundwater pollution. Integration between water level, sedimentological setting, stable isotopes, subsurface temperature and hydrochemistry were used to investigate and evaluate the problem. Water level indicates that, water logging has been occurred due to the low hydraulic load of the surface clayey layer compared to the recharged amount of water. It is also estimated using the other criteria that, the sewage water polluted groundwater in the shallow and the intermediate zones. The pollution in the intermediate zone occurred where the second silty clay layer is missed. Draining the soil and constructing the sewage pipe net are the solutions to stop water logging and groundwater pollution. Keywords: Central Nile Delta Village, Groundwater logging, Sewage pollution, Subsurface temperature, Stable isotopes, Hydrochemistry INTRODUCTION Unsewered sanitation consists of the installation of either septic tanks or pit latrines of the ventilated, dry or pour-flush types. There are important differences between the two in relation to the risk of groundwater contamination and logging (Foster et al., 1987). Septic tank soak-aways discharge at higher levels in the soil profile than pit latrines and conditions may be more favorable for pathogen elimination. Pit latrines are often deep excavations (to allow a long useful life) and the soil may be entirely removed. The hydraulic loading from septic tank soak-aways is likely to be less than for some of the pit latrine types. Septic tanks are lined and their solid effluent of high nitrogen content is periodically removed, whereas most pit latrines are unlined and the solid material remains in the ground. For these reasons, septic tanks are likely to pose a less serious threat to groundwater than pit latrines. Thus, in many large cities, the impact of unsewered sanitation may not be significant because municipal water supplies are drawn from surface water and then treated, or drawn from relatively distant and deep, well-protected aquifers. Often the most serious problems arise in medium to smaller sized towns and in densely populated peri-urban and rural areas where local, shallower, and often untreated, groundwater sources are