# Water Supply Systems for Settlements with Arsenic-Contaminated Groundwater--Making the Right Choice
## 3 Results and Discussion
### Central Supply Approach
#### 3.4.2 Central Supply Approach for Senta  
None of the settlements in the municipality of Senta have good quality groundwater sources. As mentioned above, the system, therefore, relies on the water source and WTP in Tresnjevac (K11) in Kanjiza municipality and also encompasses nearby Adorjan (K12), which is only 2.9 km from the source. The water quality in Tresnjevac (<10 ug/L As, 0.57 mg/L Fe) is similar to the water in Velebit (<10 ug/L As, 0.74 mg/L Fe) and as such also only requires treatment Scheme B to provide safe drinking water.  
In Senta municipality, as the preliminary analysis shown in Figure 12 demonstrates, it is not economically justified to connect the peripheral settlements Kevi (S3) and Tornjos (S4) with the Senta microsystem. The investment value of the pipeline from Bogaros to these  
Figure 11: Configuration of the Kanjiza microsystem.  
two settlements (about EUR 700,000 in total) significantly exceeds the investment value of the local water treatment plants (about EUR 460,000). Therefore, these two villages were left outside the Senta system, with the possibility of individual local treatment solutions or connection to some other microsystem.  
On the other hand, as shown in Figure 13 below, across the river Tisa from Senta are four settlements in the neighbouring municipality of Coka, which also have very poor quality water sources: Coka (S5) (about 5 km from Senta), Ostoijcevo (S6) (about 6 km from Coka) Jazovo (S7) (about 5 km from Ostoijc), and Sanad (S8) (about 5 km from Coka). The preliminary calculations revealed that the investment value of the four plants in these settlements (approximately EUR 2.15 million) is almost double the investment value of the main transmission pipelines required to connect then to Senta (approximately EUR 1.12 million). Therefore, these four villages have been included in the Senta central supply group.  
A total of nine settlements are, thus, envisaged for connection to the Senta microsystem: Senta, Gornji Breg, and Bogaros in Senta municipality; Coka, Ostoijcevo, Jazovo, and Sanad in Coka municipality; and Tresnjevac and Adorjan in Kanjiza municipality. The configuration of the system with all of the important infrastructure is shown in Figure 13.  
Water is abstracted and treated on site in Tresnjevac and directed over the main pumping station to the settlements in the system. The WTP capacity is 125 L/s, and it operates according to the technological Scheme B. Clean water flows into a pumping pool. Tresnjevac is directly connected to the main pipeline of the pumping station. Senta, Gornji Breg, Coka, Sanad, and Ostoijcevo have their own water towers, and the villages Adorjan, Bogaros, and Jazovo are supplied by booster pump plants. In front of each village, there is a pumping station. The estimated cost of the central supply system for Senta is shown in Table 7.  
Figure 12: Preliminary analysis for the municipality of Senta.  
The main pipeline extends from the main pumping station at the site of the source and WTP Tresnjevac over Gornji Breg and Senta to Coka. The network among the settlements is 43.9 km long in total and includes DN400 to DN90 pipelines. The total investment cost of the pipelines is EUR 5.6 million, which is approximately 56% of the price of the entire network, which amounts to EUR 10 million.