Mountain Goc is one of the regions with the highest water potential in Central Serbia (Yugoslavia), with specific annual runoff of 12-17 l/s per square km. Upper part of the catchment area of the Gvozdacka River has 111 springs, on the surface of 13.3 square km. 33 springs has volume yield from 0.5 to 2.5 l/s, with physical and chemical parameters of high water quality. These springs never dry up, even during years with low amount of precipitation. The upper part of the catchment area of the Gvozdacka River is under association Abieti-Fagetum, which is one of the worthiest in Serbia (Yugoslavia). Besides annual amount of precipitation, characteristics of soil, hydro-geological attributes of rock masses, influence of vegetation on processes of interception and evapotranspiration, which are very important factors for preservation of springs and their volume yield, also the system of forest ecosystems management. Not adequate measures in exploitation of forests lead to decreasing of volume yield of springs, and often to their disappearing.

During the summer 1998 the second phase of Cadastre of Water Objects on the Teaching Base Goc, on the Goc mountain, in central Serbia (Yugoslavia) was done. Investigation was carried out on the territory of 20 square km, with serpentine as parent rock. Serpentine is decomposed in the surface layer, with sceletal soil up to 50 cm deep, insignificant retention attributes. Dominate surfaces under bare lands, meadows, pastures and degraded forest stands. 35 springs were registered, small volume yield (up to 0.29 l*/s), with pH=7.5 to pH8.5, electrical conductivity from 80 up to 800 microS*/cm, temperature 7.0-17.0 deg C. Springs are permanent, but on the higher parts could dry up. Water level in the serpentine has small hydraulic gradient, with slope to the zones of out flow, in other words, to the local erosion base. Hydrogeological characteristics of serpentine were analyzed detailed.

In April 1997 and 1998 investigations of algae, Rotatoria, Cladocera, Copepoda and Hydracarina were conducted. The investigated localities were 8 small water bodies at around 800 m a.s.l., at Mali Krs, in the surrounding of Bor, Serbia (Yugoslavia). The aim was to examine composition of these groups and to give the evaluation of the quality of water. Among algae, according to the number of taxons, the dominant group was Bacillariophyta (45), then Chlorophyta (17), Cyanophyta (3), Euglenophyta (4), Xanthophyta (1) and Pyrrophyta (1). Rotatoria were present with the highest number of taxons among microfauna. In these investigations 48 taxons were present. The highest number of taxons was among Cephalodella, Corurella, and Trichocerca. Among Cladocera 4 taxons were present, and among Copepoda 9 taxons, and all the present species were found in our previous investigations. Hydracarina were present with 3 species, also with high diversity. Around two thirds of all taxons are oligosaprobionts, which indicates to the good quality of the water.

It has been done the analysis of the physical and chemical characteristics of the water from two households in the village Berkovac in the foot of the mountain Maljen, Serbia (Yugoslavia). These households are supplying from two different springs. The water from the spring "Dobracinovica izvor" is contaminated and it is not for use, but the quality of the water from the hill Kulica is satisfactory. Both of them belong to the group of cold mineral waters.

The paper presents results of microbiological quality of three drinking water sources – Ratno ostrvo, Petrovaradinska ada and Strand. The following analyses were carried out in 2010: total count of aerobic mesophilic bacteria at 37 deg C, count of organotrophs (categorization according to Kohl), aerobic facultative organotrophs, lipolytic and hydrocarbon oxidizing bacteria. Organotrophic count was determined on low nutritive R2A medium. Enzymatic activity of water was also determined and water was categorized according to index of phosphatase activity (IFA).

Nowadays people increasingly use bottled water for drinking which makes bottling a very profitable business. The aim of this paper is better understanding of physical and chemical properties as well as the contents of dominating ions and microbiological purity of 13 spring waters existing on the territory of Zlatibor region (Serbia, Serbia&Montenegro) which according to its water capacity, its watershed features and good roads availability may be further explored for the purpose of water bottling.

Slow sand filtration is an effective water treatment process. However, the performance of slow sand filters is influenced by the raw water turbidity. Filtration on pebble-matrix and roughing filters is introduced as a process effective in reduction of raw water turbidity. Efficiencies of these pretreatments documented on the raw water sources world-wide are presented in this paper as well as the investigation results from the similar raw water source in Serbia (Serbia&Montenegro).

The area of Zidine is located southwest of Belgrade, Serbia&Montenegro, in the sanitary protection zone of the existing Belgrade water source. This potential water source is capable of yielding water of better quality than that of the existing raw groundwater, for final treatment plants at Bezanija and Banovo Brdo. In view of available capacities of these plants and the raw water system, the water disposal issue is practically resolved and the water source is also highly advantageous in economic terms. Two options of preliminary treatment after settling were considered: sand filters and microfilters.

As a consequence of bombing of Novi Sad Oil Refinery, Serbia (Serbia&Montenegro), the spillage of large amounts of oil and derivatives caused hydrocarbons pollution of the area surrounding the Refinery and the river Danube, thus directly endangering the entire water source "Ratno ostro". As a measure of protection in the division zone of the Refinery and the water source area, a hydraulic barrier was constructed. Within the process of monitoring piezometer water quality and the water supplied by protection system wells, microbiological analyses of water were carried out with the aim of supervising the barrier functioning. The results have shown that bacterial populations in polluted areas exhibit a duel role: they act as bioindicators of a certain pollution, but at the same time they take part in the process of selfpurification.

Degradation of groundwater quality whish is used as a raw water source, caused by the continuous pollution, develops gradually. Therefore, it is necessary to analyze the pollution influence, on the first place by the expect concentration of hazardous substances in groundwater. Water source protection measures are based on the results of these analyses.