Put on rubber gloves and ventilate the room. Common household products such as vinegar and ammonia have less toxicity than some commercial cleaners but can still cause eye and skin irritation.
Mix together 1 cup ammonia, 1/2 cup vinegar, 1/4 cup baking soda and 1 gallon of hot water in a bucket. Then, pour the mixture in a spray bottle.
Spray the shower stall liberally with the cleaning solution and allow it to set for a few minutes.
Dampen the sponge with the cleaning solution and begin scrubbing the shower stall from the top down. For stubborn stains, dip the scrub brush in oxygen bleach or an oxygen bleach-based product and scrub until clean.
Apply a calcium and lime remover on drains and showerheads to remove hard water stains.
Rinse the entire stall with clear, warm water.