Can water be used as a alternate fuel instead of other fuels?

yes, water (H2O) can be used as an alternative fuel, by means of splitting so to speak the water into hydrogen and oxygen through an electric current, but the main problem as we all know that electricity and water can end very badly so, until there is a safe way to do so it will remain a thought, also once split the H2and the O can be reacted back in water and the energy of the splitting and the rejoining makes and endothermic reaction (gives of heat/energy (to be used as a power source for a auto mobile))