Assessment of groundwater quality and evaluation of scaling and corrosiveness potential of drinking water samples in villages of Chabahr city, Sistan and Baluchistan province in Iran

The aims of this study were to assess and analysis of drinking water quality of Chabahar villages in Sistan and Baluchistan province by water quality index (WQI) and to investigate the water stability in subjected area. The results illustrated that the average values of LSI, RSI, PSI, LS, and AI was 0.5 (±0.34), 6.76 (±0.6), 6.50 (±0.99), 2.71 (±1.59), and 12.63 (±0.34), respectively. The calculation of WQI for groundwater samples indicated that 25% of the samples could be considered as excellent water, 50% of the samples were classified as good water category and 25% of the samples showed poor water category.


Specifications
graph, figure How data was acquired All water samples were analyzed according to the Standard Methods for Examination of Water and Wastewater Temporary and permanent hardness, magnesium, calcium, and chloride were measured by titration method. The hydrogen ion concentration (pH) and electrical conductivity and opacity were analyzed with pH meter (model wtw, Esimetrwb) and turbidity meter (model Hach 50161/co 150 model P2100Hach, USA), respectively. Also, fluoride, nitrate, and sulfate were determined with Hach DR5000 spectrophotometer and compared with internal standards. Data format Raw, analyzed Experimental factors The mentioned parameters above, in abstract section, were analyzed according to the standards for water and wastewater treatment handbook.

Experimental features
The levels of physical and chemical parameters were determined.

Data source location
Chabahar, Sistan and Baluchistan province, Iran

Data accessibility Data are included in this article
Value of the data 1. These data could be helpful for many organizations, such as rural water and wastewater organizations, water treatment plants, water resources management, and the Ministry of Energy, which need these to make decisions and adopt guidelines for water quality management. 2. The zoning of the scaling and corrosion indices and water quality index (WQI) was done to provide a clear picture of the water quality in the water resources at the villages of Chabahar. 3. In dry and semi-arid climates such as Iran, groundwater is almost the main source of water supply, therefore, the continuous monitoring of the quality of these valuable resources is very necessary.

Data
The parameters and indices were calculated in the experiments are including chloride ion, sulfate, temperature, Electrical Conductivity (EC), Total Dissolved Solids (TDS), pH, total alkalinity, bicarbonate ions, and calcium hardness according to standard methods for examination of water and wastewater [1]. Then LSI, RSI, PSI, LS, and AI were used to evaluate the water stability. Fig. 1 shows the sampling locations and Table 1 presents the indexes, equation, and some definition and criteria for categorizing the stability of the water. The chemical and physical properties of drinking water are presented in Tables 2 and 3. Table 4 shows the water stability indices in different parts of the region studied. As seen in Table 4, 7.5, 30, 80.72.5, and 97.5% of water supplies of Chabahar were corrosive according to the obtained results from LSI, RSI, LS, PSI, and AI, respectively (Fig. 2). Estimated corrosion indexes with GIS software are shown in Fig. 3. In the following we calculated water quality index (WQI).
An important parameter for determining the water quality and its sustainability for drinking purposes is water quality index (WQI). In order to provide the composite influence of individual water quality parameters on the overall water quality WQI could be useful [2]. Also according to World Health Organization (WHO) 2011 standards calculating the WQI has been considered for drinking water quality assessment. The relative weight (Wi) was assigned for water quality parameters based on their relative importance on water quality for drinking purposes ( Table 5). The water quality classification based on WQI values is shown in Table 6. The calculation of WQI for groundwater samples is shown in Table 7. A total of 40 samples were analyzed for WQI. Among these, 25% of the samples showed excellent water, 50% of the samples fell under good water category and 25% of the samples showed poor water category respectively (Fig. 4). Table 1 Corrosion and saturation indices, equation and criteria for categorizing the stability of the water used in the study [3,4].

Equation
Index  2. Experimental design, materials and methods

Study area description
Chabahar city in Sistan and Baluchistan province and its aquifers are located in South-East Iran between the latitudes 25°17′ N and longitudes 60°37′ E, encompassing an area of about 9739 km 2 (Fig. 1). The study area is a semi-flat plain region with a gentle slope toward the south has a warm, temperate climate. Also the air's highest and lowest temperatures are 50°C and −7°C, respectively, with an annual average of 25°C. The subjected area was classified as a semiarid, and the precipitation

Sample collection and analytical procedures
In this cross-sectional study, 40 rural drinking water sources in Chabahar villages in Sistan and Baluchistan province were analyzed during 12 months (2010-2011) according to physical and chemical parameters. Fig. 1 shows the study area and sampling locations in this study. Samples were collected in polythene bottles (1L) and then immediately transported at 4°C to the central laboratory of the water and wastewater company. All water samples were analyzed according to the Standard Methods for Examination of Water and Wastewater and using titration method permanent hardness, magnesium, calcium, and chloride were measured [1]. The concentration of hydrogen ion (pH) and electrical conductivity and opacity were also analyzed with pH meter (model wtw, Esimetrwb) and water purposes, as shown in Tables 6 and 7 and the Langelier saturation index, Ryznar saturation index, Aggressiveness index, Larson-Skold index, and Puckorius scaling index were calculated and the results were classified in three categories: scaling, stabilized, and corrosive. Table 1 presents the indices, equations and some definitions and criteria for categorizing the stability of the water. Finally, the severity of corrosion in different water supply systems of Chabahar villages in Sistan and Baluchistan province was displayed using a geographic information system (GIS). All analyses were done using Excel 2010 and Arc GIS 10.3 software.

Water quality index calculation
To calculate the WQI, the weight for the physico-chemical parameters were assigned according to the relative importance of parameters in the overall quality of water for drinking purposes.
Using the following equation, the relative weight was computed: Wi is the relative weight Wi is the weight of each parameter n is the number of parameters.
The quality rating scale for each parameter is calculated by dividing its concentration in each water sample by its respective standards (World Health Organization 2011 [5]) and multiplied the results by 100.
where qi is the quality rating Ci is the concentration of each chemical parameter in each sample in milligrams per liter Si is the World Health Organization standard for each Table 5 Relative weight of chemical of physico-chemical parameters [5].

Number Factor
Factor Weight WHO Standard  Table 6 Water quality classification ranges and types of water based on WQI values [6]. For computing the final stage of WQI, the SI is first determined for each parameter. The sum of SI values gives the water quality index for each sample.

WQI value Class Explanation
SIi is the sub-index of it parameter qi is the rating based on concentration of it parameter n is the number of parameters [2]