The influence of sludge on the groundwater’s quality has been shown on the bases of the agricultural exploitation of the sludge from a sewage-treatment plant. Little thickness of unsaturated zone (8.8 m) is not effective protection against the infiltration of the pollution from the surface. Unsaturated zone consist of sand of permeability coefficient k=0,68 m/h. The time of the vertical infiltration into the aquifer has been estimated at t=14,4 days. The investigations carried out during fertilization with the sludge have revealed an undoubted increase in the concentration of some ions as well as the increase in pH of the groundwater. The increase in the amount of some ions (e.g. N-NO3, SO4, Zn) as well as detergents indicates the possibility (as function of time) of reaching higher values than the ones permissible for drinking water. The phenomenon of the increase in the concentration of the particular ions will be accelerated after depletion of sorption of the soil in the unsaturated zone. The time can be estimated for not more than several years, taking into account a small area of the fertilized fields and high contents of “pollution” in the sludge (the total of the heavy metals reaches up to 1,5 g/kg)

In paper an influence of waste dump “Chrobrów” on groundwater and tributary of the Bóbr river was described. This waste dump was installed in former gravel excavation. For first 10 years it had no leak stopper and sewage water could freely infiltrate. Geological structure of the waste dump subsoil is unfavourable because garbage are directly stored on gravels with high filtration coefficient which make migration of pollutants easy. At the moment the waste dump has a leak stopper made from bentonite composite but there are still polluted groundsunderneath. In this paper was analyzed data about ground- and surface water quality from years 1994 – 2004. It was found that the quality of groundwater deteriorated, especially in years 1999 and 2002. The most worsening was noted in case of chlorides, ammonia nitrogen, sodium and potassium. Unfortunately there is no data before 1994 so there is no information about hydrogeochemical background. Increased values of all groundwater components infirst period of investigation are results of exploitation in years 1984 – 1994, when waste dump had no leak stopper.But later deterioration of groundwater quality can not be explained in this way. It should be drawn a conclusion that the seal of waste dump bottom does not work correctly. It was found that there is no negative impact of waste dump on surface water what is caused by absence of hydraulic contact between river and groundwater on investigated area.