Magnesium is an essential mineral element for human beings. The daily requirement of magnesium is about 0.7 gms. Magnesium is considered relatively non-toxic to man and not a public health hazard because before toxic concentration are reached in water, the taste becomes quite unpleasant.
Like humans, animals also require magnesium salts in their diet. Magnesium salts act as cathartics and diuretics among animals as well as human beings. ,High concentrations in drinking water may cause scouring diseases among livestock and wildlife.
Magnesium is essential to normal plant growth because it is an important component of the chlorophyll molecule. Magnesium also is important in irrigation water because it tends to keep the soil permeable and in good health.
Among U.S. waters supporting a good fish fauna, ordinarily 5% have less than 3.5 mg/L of magnesium, 50% have less than 7 mg/L of magnesium and 95% have less than 14 mg/L of magnesium.