I don't think you can classify ligands as low or high spin - you either call them low/high FIELD (with high field ligands typically giving low spin complexes and vice versa), or simply low/high in the spectrochemical series, right?
Water doesn't invariably form high-spin complexes though. For example, [Fe(H2O)6]3+ is right on the verge of the high/low spin transition at room temperature and even a small change in temperature can shift which way it goes. This actually has some important consequences for reaction rates (which you'll learn about in your 3rd year Inorganic reaction mechanisms course).