I'd get a soup plate and then slide the glass very carefully over to the edge of the table, and let the water run into the soup plate - it doesn't have to run onto the floor.
僕ならスープ皿を持ってきて、グラスを充分に注意しながらテーブルの端まで滑らせて水をそのスープ皿に流し込むな。水は床にはこぼれない。