To clean a rain shower head, remove it and place it in a bucket of distilled white vinegar. Allow it to sit for a few hours before scrubbing away any remaining residue. This will aid in the removal of mineral deposits from your shower head, which can cause the flow to slow or become blocked entirely. Keep your shower head and bathtub area clean (especially of soap scum) so that mineral deposits don't cling to it and cause hard stains and clogs. You can also buy a portable steam cleaner to finish the job faster than hand-scrubbing.