Distilled, reverse osmosis, or deionized water or rain water are better choices for watering plants to prevent mineral accumulation in the soil. Or, if using softened water, water heavily to wash previously deposited minerals through and beyond the plants' root zones. Heavy sodium or potassium salt concentrations in the absence of calcium or magnesium may affect swelling of soils and retard the growth of plants.

For outside sprinkling purposes the use of softened water is, first and foremost, wasteful. Again, where the concentration of hardness minerals is heavy, the sodium salts replacing them might retard growth and might be sufficient to kill the grass.