The underground Quaternary water in the neighbourhood of working municipal waste dump was sampled from 3 piezometers and analyzed for pH, sp. cond., ammonia and nitrate N and org. C in 2004-2007 to predict the trends for 2008-2010. A permanent and substantial decrease in the water quality was obsd. In particular, a high increase in ammonia N content (up to 3.52 mg/dm(3)) and water salinity (sp. cond. up to 1100 iS/cm) was evidenced.