If the water marks are dark, they are in the wood and the finish must be removed to solve this problem. If the water marks are light or white, they are in the finish and this can be solved with Wood Elixir. On a shellac finish, Wood Elixir alone will remove the marks and seal the finish. On a lacquer finish, even the toughest stains can be removed with Wood Elixir applied with 0000 steel wool. I don't know what other products you have tried but, I have never found one that works regardless of their claims. Without telling how, I can assure you that Wood Elixir works.... or your purchase price will be refunded.