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Table 1 Statistical summary of the physicochemical parameters of borewell water samples collected from the study area

From: Investigating aquifer contamination and groundwater quality in eastern Terai region of Nepal

Parameters Range Mean Standard deviation Median WHO guidelines NDWQS guidelines Samples not within limit
Number %
Borewell (N = 135)
 pH 5.00–8.36 6.946 0.574 7 6.5–8.5 6.5–8.5 25 18.52
 Temp (°C) 17.8–34.8 28.064 4.229 28.7
 EC (µS/cm) 14.8–1192.0 433.797 233.926 433 1500 0 0
 Turbidity (NTU) 0.00–93.00 13.508 20.929 3.44 5 5 63 46.67
 Color (Hazen) 0.01–4.10 0.235 0.513 0.11 15 5 0 0
 TDS (mg/L) 7.50–596.00 223.690 115.611 219.5 1000 1000 0 0
 F (mg/L) 0.02–1.04 0.232 0.193 0.18 1.5 0.5–1.5 0 (119) 0 (88.15)
 NH3 (mg/L) 0.05–2.53 0.479 0.407 0.38 1.5 1.5 5 3.70
 NO3 (mg/L) 0.05–2.83 0.187 0.408 0.05 50 50 0 0
 Cl (mg/L) 0.50–145.45 13.424 24.223 3 250 250 0 0
 TH (mg/L) 1.11–510.00 190.875 87.955 205.35 500 1 0.74
 CH (mg/L) 1.00–412.62 119.419 66.504 117.89
 TA (mg/L) 2.36–512.40 196.491 90.848 209.72 500 1 0.74
 Fe (mg/L) 0.05–23.10 2.030 3.945 0.59 0.3 0.3 87 64.44
 Mn (mg/L) 0.05–3.10 0.356 0.463 0.22 0.2 70 51.85
 As (mg/L) 0.005–0.050 0.005 0.004 0.005 0.01 0.05 1 (0) 0.74 (0)
 Ca2+ (mg/L) 0.00–165.05 45.598 26.418 42.708 200 0 0
 Mg2+ (mg/L) 0.00–57.07 18.118 12.255 16.53
Tubewell (N = 40)  
 pH 5.27–8.59 6.978 0.669 6.965 6.5–8.5 6.5–8.5 9 22.5
 Temp (°C) 17.0–35.9 26.563 5.603 28.5
 EC (µS/cm) 32.2–1898.0 484.998 350.855 461.5 1500 (1) (2.5)
 Turbidity (NTU) 0.00–149.00 10.100 24.444 1.915 5 5 15 37.5
 Color (Hazen) 0.01–1.03 0.164 0.202 0.125 15 5 0 0
 TDS (mg/L) 42.00–949.0 255.820 164.383 235.0 1000 1000 0 0
 F (mg/L) 0.04–1.10 0.245 0.283 0.14 1.5 0.5–1.5 0 (33) 0 (82.5)
 NH3 (mg/L) 0.05–3.36 0.472 0.545 0.38 1.5 1.5 1 2.5
 NO3 (mg/L) 0.05–3.38 0.536 0.879 0.11 50 50 0 0
 Cl (mg/L) 0.50–161.80 29.118 40.772 8.0 250 250 0 0
 TH (mg/L) 35.00–349.0 194.241 88.628 204.5 500 0 0
 CH (mg/L) 13.35–270.26 116.957 65.504 107.045
 TA (mg/L) 36.4–368.88 201.681 87.762 215.67 500 0 0
 Fe (mg/L) 0.05–10.81 1.184 2.271 0.315 0.3 0.3 20 50
 Mn (mg/L) 0.05–2.75 0.402 0.564 0.15 0.2 (18) (45)
 As (mg/L) 0.005–0.005 0.005 0.000 0.005 0.01 0.05 0 0
 Ca2+ (mg/L) 5.34–108.10 43.580 25.797 40.079 200 0 0
 Mg2+ (mg/L) 1.46–61.49 19.889 13.907 15.556
  1. Numeric values within bracket represent samples number and percentage of samples not within limit as per NDWQS guidelines while those outside are as per WHO guidelines
  2. EC electrical conductivity, TDS total dissolved solutes, TH total hardness, CH calcium hardness, TA total alkalinity, WHO World Health Organization, NDWQS Nepal Drinking Water Quality Standard