Add water to a plastic freezer bag, then add the shower head to the bag.

Add about one cup of distilled white vinegar to the plastic bag. Seal the plastic bag, and let the shower head rest for about two hours.

Depending on the severity of the mineral deposits, you can let the showerhead rest in the solution for up to 8 hours.

Be careful when using distilled white vinegar as it can leave stains; also, be careful when pouring it, as it can cause damage if the solution gets into your eye.