The concentrations of the minerals magnesium (Mg2+), calcium (Ca2+), sodium (Na+) and potassium(K+) were determined in tap, filtered and bottled waters in Bahrain using atomic absorption spectroscopy. Tap and filtered water samples were obtained from the households of ten different cities in Bahrain, while twenty different commercial brands of bottled water samples were purchased from supermarkets and hypermarket in Bahrain. Significant differences (p<0.05) were recorded between the pH values of tap, filtered and bottled water samples. The pH valuesfor allwater samples ranged between 6.61 and 8.39 in whichthe lowest concentration was recorded in filtered water samples (6.96 ± 0.24), whereas bottled water samples had the highest values (7.63 ± 0.27). Filtered water samples also had the lowest magnesium concentration (0.67 ± 0.52 mg/L) in comparison to bottled water samples (13.79 ± 9.80 mg/L) and tap water samples (1.825 ± 1.08 mg/L). Calcium concentration was significantly higher (p<0.05) in tap water samples (64.95 ± 5.35 mg/L), whereas the lowest concentration was recorded in bottled water samples (17.87 ± 18.68 mg/L). Tap water samples also had significantly higher (p<0.05) sodium concentration (15.67 ± 3.93 mg/L) compared to filtered water samples (9.02 ± 2.41 mg/L) and bottled water samples (8.53 ± 9.59 mg/L). Potassium was found to have the lowest concentration in filtered water samples (1.60 ± 1.67 mg/L), whereas no significant differences was recordedbetween tap water samples (3.76 ± 1.39 mg/L) and bottled water samples (3.63 ± 4.03 mg/L). The findings of the present study have indicated that in terms of all components investigated, the quality of tap water in Bahrain is better than filtered water and with minor improvement in the concentration of magnesium can be considered as good as bottled water. © BEIESP.