Complex sentence: Although a manometer may use any fluid in principle, common fluids like water give heights that can't be contained in a normal room-water is of the order of 10 metres to give atmospheric pressure.
Split into simpler sentences: Although a manometer may use any fluid in principle, common fluids like water give heights that can't be contained in a normal room. A water column needs to be of the order of 10 metres to give atmospheric pressure.