I'm guessing that if you live in Southern California, the chances are pretty great that you do.

Here's a tip on how to solve the problem of a clogged shower head. If possible, remove your shower head and soak it in a mixture of 1 cup vinegar in 1 quart water for at least 15 minutes. If it is a plastic shower head, use equal parts of vinegar and water and soak for an hour. By now you should be able to remove the dissolving deposits with a brush, and rinse away.

If your shower head is impossible to remove, you can make a soaking bag for it by filling a plastic bag with vinegar solution and fasten it to the shower head with some string or a rubber band. Let it soak overnight and by morning the clogging should be dissolved and your shower head nice and clean.