I had never experienced hard water until I moved to IL and when we moved into our current apt the shower head was so clogged that it resembled a leaky faucet more than anything. It was getting difficult to shower and annoying as hell so I knew something had to be done. I wanted to try to clean the shower head using products as natural as possible and after doing some research online I decided to try a few methods.
Method #1: So one method I found suggested that I pour a mixture of white vinegar and water in a plastic bag and then tie that bag around the shower head while submerging it for at least an hour. Result: Fail, 2% clear. I guess maybe "Fail" isn't an accurate description. This method helped as much as a 10 year old can "help" you with your taxes ... maybe a little but not much. Tying the bag around the shower head while keeping it submerged was actually really difficult because of air bubbles and gravity pulled the bag down little by little.
Method #2: I figured the degree of hard water built up on this bad boy needed full strength, 100% white vinegar with no dilution. So the next method I tried I unscrewed the shower head, tapped out any debris from the back end (by the way, YUCK!, see picture below), put the shower head in a tall cup, poured baking soda inside the back end of the head, poured enough white vinegar (slowly) to submerge it, and let it set for a couple of hours. Result: A little better, 50% clear. It still wasn't the free flowing shower head that I knew it could be.
Method #3: Last thing I did was to repeat the baking soda +100% (non-diluted) white vinegar method but this time I let it sit submerged over night, 8+ hours. Result: 98% clear! There were only a few holes that were still slightly dribbling water so I used a safety pin to poke through the last remaining clogged holes and after that I was golden!
After proudly announcing that I had successfully unclogged the shower head to my sweet hubby he then immediately suggested we get a brand new shower head with a hose so we could wash the dog in the tub. Bastard.