Water stains and soap scum create fiberglass shower walls appear gloomy and leave behind an unattractive haze on glass shower doors. Hard water, that includes lime, calcium along with other minerals, may make water spotting even worse and more challenging to eliminate. A reasonably acidic cleaner helps cut through the stains and scum. Although commercial abrasives can scrub away spots, they also roughen up and etch fiberglass and may leave scratches on glass doorways.

Fill a spray bottle with undiluted vinegar, which may cut through soap scum and water stains. Alternately, locate a nonabrasive bathtub and tile cleaner formulated for water stains.

Spray the fiberglass shower walls and the glass shower door liberally using the vinegar or bathtub cleaner. Allow the cleaner or vinegar to soak on the walls and doorway for few minutes so it could loosen the water stains and soap scum.

Wipe the walls and doorway dry using a nonabrasive rag. Inspect the walls to any residual water stains.

Mix two parts baking soda with one part water to produce a thin paste, if stubborn stains remain after the initial cleaning. Baking soda is not as abrasive than industrial abrasive cleaners are, which makes it more acceptable for cleaning fiberglass and glass without etching.

Rub the paste onto the shower door and walls, paying particular attention to some areas with stubborn stains. Scrub gently with a moist rag.

Rinse the paste from the walls using warm water. Spray and wash a second time with the vinegar or bathtub cleaner if any soap residue or streaks stay; otherwise, a warm-water rinse is adequate. Wipe dry.

See related