Your softener's water and salt use will fluctuate based on the size of the recharge triggered. The size of those cycles are based on your water usage patterns and the quality of incoming water. You can find a few examples of water and salt use in the Specifications chart in your Owner's Manual. Note: Manual recharges will always use the maximum salt/water dose.
Example: Highlighted below is the maximum amount of salt and water this system could use in one recharge - 35.2 gallons of water @ 13.1 lbs of salt use.