I am going to guess you are one of our neighbors to the North( canadian). In my neck of the woods, Souteastern USA this would not be a problem, with at least 6 inches of fill between each, I would still talk with each utility and get their blessing on the project. If it were my project the trench would be 30 inches deep, electric on the bottom, 6 inches of fill then gas, 6 inches of fill then water, this would give the water pipe about 16 inches of cover, plenty in my area to prevent freezing. This arrangement also means that any one who accidentily digs in to this area is likely to hit the water line first and maybe stop digging before te gas or power is cut.
Life is tough, Life is tougher when you are stupid