Heavy metals analysis and quality assessment in drinking water – Khorramabad city, Iran

Continuous monitoring of drinking water quality is essential in terms of heavy metals and toxic substances. The general objective of this study were to determine the concentration of heavy metals in drinking water of Khorramabad city and to determine the water quality indices (The heavy metal pollution index and heavy metal evaluation index). According to the city map, 45 points were selected for drinking water sampling through the city distribution system. The results of this study showed that the average concentration of heavy metals such as Zn, Pb, Cd, Cr, and Cu were 47.01 μg/l, 3.2 μg/l, 0.42 μg/l, 5.08 μg/l, and 6.79 μg/l, respectively. The HPI and HEI (water quality indices) for Zn, Pb, Cd, Cr, and Cu were 46.58, 46.58, respectively. According to the indices, the city drinking water quality is good in terms of heavy metals.


Subject area
Chemistry, biology More specific subject area Water monitoring and quality Type of data Measuring the concentration of heavy metals (Zn, Pb, Cd, Cr, and Cu) in the samples of drinking water distribution system. After determining the concentration, water quality pollution indices were calculated.

Experimental features
According to the city map, 45 points of drinking water in distribution system were selected as sampling point. Until concentration measurement, all samples were stored in standard conditions and were analyzed for heavy metals Data source location Khorramabad city Iran (33°48′ N, 48°35′ E)., Lorestan province, west of Iran

Data accessibility
Data are included in this article and supplemented excel file

Value of the Data
There is always the possibility of contamination of water resources with heavy metals and toxic substances, therefore, continuous monitoring is essential.
Heavy metals can accumulate in human body and other living organisms over a long period and may cause adverse effects on human health.
The main sources of heavy metals contamination in drinking water including heavy metals leakage through iron pipes in distribution systems and due to geological contamination of the region that water originates from.
One of the most important methods for drinking water quality determination is the measurement of heavy metal pollution by indices, so, heavy metals data can be used for determination of the water quality indices determination.

Location data
Khorramabad, one of the cities of Lorestan province, located at west of Iran (33°48′ N, 48°35′ E). Fig. 1 shows the location of the city and the sampling points the study area. The city area is about 6233 km 2 . Based on the latest population census in Iran (2016), its population was 506,471 persons.

Experimental design, materials, and methods
In this study, 45 stations were selected as sampling points in a way that covers the whole city distribution system. Sampling was performed according to a standards procedure. The collected samples were also kept in accordance with standard methods for water and wastewater. Further, ICP-OES (Instrument Model: Varian VISTA-MPX) was used to measure the concentrations of heavy metals. Table 1 shows the concentration of measured heavy metals.
After determining the concentration, water quality pollution indices were calculated. The heavy metal pollution index (HPI) indicates the overall quality of the drinking water in terms of heavy metals [1][2][3][4][5][6][7]. This index is calculated according to Eqs. (1) and (2) as follows: where, Q i and W i are the sub-index of the ith parameter and the unit weightage of the ith parameter, respectively. n is the number of parameters considered. M i , I i , and S i are the monitored values of heavy metal, ideal and standard values of the ith parameter, respectively. The sign (−) indicates the numerical differences of the two values, ignoring the algebraic sign. Water quality based on HPI can be classified into three categories including: low (less than 100), the threshold risk (equal to 100), and high (more than 100). If HPI is more than 100, water cannot be used for drinking. Measured values of HPI index for the drinking water samples are presented in Table 2. Heavy metal evaluation index (HEI)  is a method of estimating the water quality with focus on heavy metals in drinking water [4,[6][7][8][9][10]. This index is calculated according to Eq. (3), as follows: where, H c and H mac are the monitored values and maximum admissible concentration of the ith parameter, respectively. The classifications of the HEI index is as follows: low (less than 10), medium (between 10 and 20), and high (more than 20). Tables 2 and 3 show the used constants and the values of the calculated HPI and HEI, respectively [11][12][13][14].