Remove water stains from basement walls by cleaning the area with a mixture of water and vinegar or a commercial cleaner. Once dry, repaint the walls with a stain-blocking primer and a fresh coat of paint. Address the underlying moisture issue to prevent future stains.

Clean stains with water and vinegar or a commercial cleaner, then repaint with a stain-blocking primer and fresh paint. Address underlying moisture issues to prevent future stains. Effective stain removal and prevention require addressing both the stains and their causes.