Soaking glassware in white vinegar is a widely recommended method for removing hard water stains. The acetic acid in vinegar is effective in dissolving mineral deposits, the primary component of hard water stains. Prolonged soaking allows the vinegar to penetrate and break down these deposits, making them easier to rinse away. This method is valued for its simplicity and the use of a readily available, natural cleaning agent.

Vinegar soak.