Water can damage wood if the exposure to moisture is excessive, degrade and stain wood, and cause structural damage. Outdoor wood is at higher risk for water damage than indoor wood since it is continually exposed to outdoor elements.
Indoor wood furniture is also at high risk for water damage, regardless of whether or not it has been treated with a finish. Water from plant vases and moisture from water glasses can penetrate a wood finish, especially if that finish is aged. Furniture polishes and wood wax help to build a protective barrier between the source of moisture and the wood.