# Water Supply Systems for Settlements with Arsenic-Contaminated Groundwater--Making the Right Choice
## 3 Results and Discussion
### Drinking Water Requirements and Socioeconomic Position of the Investigated Area
In the upper part, to a depth of approximately 60 m, free aquifers were formed (the first aquifer), and below them are the pressureised atresia aquifers. The quality and quantity of these aquifers encompass a wide range, from the size of the aquifers, capacity, and water restoration method to the water quality, which varies from waters that correspond to the drinking water quality standards to groundwater, which requires highly complex treatment procedures. A summary of the more problematic drinking water quality parameters for the water sources used by the municipalities and settlements in the area covered by this paper is given in Table 3.  
The analysis focused on the determination of arsenic and other parameters that are important for the correct selection of the required drinking water treatment technologies. The obtained results show that the water quality in these two municipalities is generally unsatisfactory. The groundwater quality data, as presented in Table 3, indicate that the amount of arsenic in the main settlements of interest is 5 to 9 times higher than the MAC value given in Serbian regulations [10]. The groundwater source in Senta also contains higher amounts of Fe than the MAC value. In addition, despite the fact that the oxidisability is not higher than the MAC, the high TOC values (above 2 mg C/L) indicate that NOM is present in concentrations higher than recommended for microbial growth prevention [23]. This must be taken into consideration when the treatment and distribution system is \begin{table}
\begin{tabular}{l r r r r} \hline
**Data Type** & **Serbia** & **Vojvodina** & **Kanjiza** & **Senta** \\ \hline Area (km\({}^{2}\)) & 88,499 & 21,614 & 399 & 294 \\ Settlements & 6158 & 467 & 13 & 5 \\ Inhabitants & 6,834,326 & 1,825,982 & 23,039 & 21,120 \\ Population density (per 1 km\({}^{2}\)) & 77.2 & 84.5 & 57.7 & 71.8 \\ Average age & 43.5 & 43.1 & 44.1 & 43.8 \\ Number of households & 2,487,886 & 696,157 & 10,097 & 9383 \\ Number of employed & 2,273,591 & 596,668 & 5710 & 5775 \\ Average salary before taxes and & 65,864 & 62,494 & 54,419 & 59,431 \\ contributions, per employee & & & & \\ Water supply data & & & & \\ Number of households connected to the & 2,160,943 & 672,460 & 10,097 & 8195 \\ water supply network & & & & \\ Total captured water, (thousands of m\({}^{3}\)) & 686,664 & 154,736.7 & 1259 & 1245 \\ Delivered drinking water & & & & \\ (thousands of m\({}^{3}\)) & 445,409 & 112,508.3 & 1167 & 909 \\ Realisation of investments in new fixed & & & & \\ assets in the field of water supply and & 114,477 & 40,961 & 304 & 164 \\ wastewater management (EUR 1000s *) & & & & \\ Employees in the field of water supply & 35,621 & 8945 & 59 & 103 \\ and waste management & & & & \\ \hline \end{tabular}  
* Original costs reported in Serbian Dinar, converted at RSD 118 to EUR 1.  
\end{table} 
Table 2: Socioeconomic and water supply data in 2021 [20]. planned. In terms of physical and chemical quality, it is necessary to innovate or install water treatment technologies in order to satisfy the Serbian drinking water regulation [10]. Overall, these findings indicate that both Kanjiza and Senta face challenges to secure sufficient resources to invest in water supply and related infrastructure compared to the wider Vojvodina region and the country of Serbia as a whole. A more detailed breakdown of the water requirements of the settlements analysed is given in Table 4. Note that this table also includes certain settlements from neighbouring municipalities, which because of their geographical proximity to Kanjiza and Senta are sensible candidates for inclusion in the centralised water supply systems proposed in this work.