The concentration of HMs in well water (n=222) Concentration (mg / L) HMs Min Max Mean No sample over MLs (n,%) ML National Standards 01: 2009/MOH As 0.01 0.48 0.06 185 (83.33) ≤ 0.01 Pb 0.01 0.42 0.12 210 (94.59) ≤ 0.01 Cd 0.00 0.15 0.03 188 (84.68) ≤ 0.003 Cr 0.02 0.82 0.25 166 (74.77) ≤ 0.05 Hg KPH - - 0 (0.00) ≤ 0.001 The percentage of well water samples which did not meet the national standard in HMs were highest with Pb (94.59%), then followed by As, Cd, and Cr.