# Water Supply Systems for Settlements with Arsenic-Contaminated Groundwater--Making the Right Choice
## 3 Results and Discussion
### Central Supply Approach
#### 3.4.1 Central Supply Approach for Kanijza  
By analysing the quality of the groundwater in the vicinity, it was concluded that the nearest location with higher-quality water is the village of Velebit (K1), located 11.6 km from Kanijza. The groundwater at the Velebit (K1) site only requires aeration/degasification, retention, and sand filtration prior to disinfection (Scheme B, Table 1). The prelimi \begin{table}
\begin{tabular}{l r r} \hline \hline \multicolumn{1}{c}{**Facility**} & \multicolumn{1}{c}{**Investments (EUR)**} & \multicolumn{1}{c}{**Operating Costs (EUR/Year)**} \\ \hline WTP & 4,389,500 & 1,015,500 \\ Water towers & 1,203,500 & 7200 \\ Pumping pools & 84,000 & 3000 \\ Pumping stations & 155,500 & 52,000 \\ Booster pumps & 13,500 & 500 \\ TOTAL & 5,846,000 & 1,143,000 \\ \hline \hline \end{tabular}
\end{table} 
Table 6: Total costs of local supply for all 5 settlements of Senta—each with its own WTP. nary analysis is shown in Figure 10, depicting the diameter and distance of the pipeline network required. This preliminary analysis immediately eliminated the four peripheral settlements in the south-western part of the municipality: Orom (K8), Novo Selo (K7), Doline (K2), and Totovo Selo (K9). Although they are relatively close to one another and not far from Velebit, their good quality water means there is no economic justification for connecting them to the Velebit source: the investment value of the transmission pipeline from Velebit to these four villages (approximately EUR 1,372,000) largely exceeds the investment value of the local water treatment units (about EUR 885,000, including the WTP and local distribution facilities). Therefore, these settlements were left outside of the Kanjiza system, with the  
Figure 10: Preliminary analysis for the municipality of Kanjiza. possibility of individual water treatment or connection to some of the other microsystems. The villages of Mali Pesak (K5) and Male Pijace (K4) were also eliminated from the common water supply system using a similar principle, best explained by comparing the cost of the transmission pipeline per user connected. Mali Pesak (K5) has a very small population (94 inhabitants), which makes the pipeline cost for the connection to Mali Pesak approximately EUR 3500/user. This compares very unfavourably to the costs otherwise considered in the preliminary analysis. For example, in the case of Martonos (K6) and Horgos (K10), the total cost of the pipelines are EUR 115/user and EUR 160/user, respectively, an order of magnitude less. Having, therefore, eliminated Mali Pesak, although Male Pijace is larger (population 1811), it is almost twice as far from the nearest node, and the cost of the pipeline is approximately 30% greater than its local WTP would be, so it was also excluded from the centralised system. The pipeline to Martonos (K6) and Horgos (K10) was only 3% higher than the estimated value of their local WTPs, so these villages were included in the centralised supply network, as the benefits of centralisation are assumed to justify this relatively small extra cost. Tresnjevac (K11) and Adorjan (K12), at the southern part of municipality, were also not considered for connection to the central system in Kanjiza. This is because the water source at Tresnjevac is necessary for the central system of Senta, in which case connecting Adorjan to the Senta system is logical because of its proximity to the path of the transmission pipeline (see Section 3.4.2). On the other hand, just across the river Tisa, Novi Knezevac lies about 5 km from Kanjiza and has very poor quality water. The analysis determined that the investment value of just the WTP in Novi Knezevac (EUR 1,210,000) was considerably higher than the estimated value of the transmission pipeline (EUR 461,000), and Novi Knezevac was, thus, included for connection to the central system of Kanjiza. To summarise the preliminary analysis, the central Kanjiza system relies on a water source and WTP in the village of Velebit.