electrolytes and other solutes which are present in impure water are important in maintaining cellular homeostasis
But they're barely present. Adding up the common ones, calcium, sodium, magnesium doesn't even get you to 100mg per liter. Meanwhile, the body needs at least 1000mg of calcium, which is 30 liters worth.
As one might expect, water simply isn't a big source of nutrients. Anyone telling you otherwise is trying to sell you something, probably either bottled water, or mineral-powder to add to osmotic filters.