Hypertension is considered as the third risk factor in Death Triangle caused by cardiovascular diseases, in association with LDL-c and is named the dormant killer. This study involved 8122 rural residents of 36 villages in Sabzevar, whose drinking water were ranked light , relatively light, relatively hard, hard and extremely hard. Information on the total hardness, Calcium, Magnesium, Potassium, Sodium and chlorine were obtained from the municipal Sewerage office. Then, Systolic and diastolic bp of all 30 to 60 - year - old residents of the villages were measured and the correlation between water hardness and bp rate were calculated using Pearson correlation coefficient and regression. The study data revealed that the more the water hardness, the higher will be the systolic and diastolic measurements. Also, there was a significant positive correlation between systolic readings and water hardness and the ratio of Sodium and potassium. However, the correlation between diastolic reading and total water hardness was negatively significant; it was positively significant for the ratio of sodium and potassium. The study revealed that the higher the water hardness (which enhances the sodium content), the higher the bp measurements in people drinking it.