You can even fill a ziplock bag and tie it on a faucet.
If your water is really hard, pour vinegar into that little tube in your toilet too, the jets get clogged easily and that flushes them out and prevents them from blocking up. If they are blocked, the vinegar will eventually open them up if you don't regularly.
Obviously water softener if you don't have one, but depending what your waters like you may have to do more.