It would all of the above. As you need all of them for a healthy body.
Calcium and magnesium dissolved in water are the two most common minerals that make water "hard." The degree of hardness becomes greater as the calcium and magnesium content increases and is related to the concentration of multivalent cations dissolved in the water.
Cardiovascular is probably your answer
Cardio- the heart
Vascular- vessels
Circulatory- blood