Basically the purpose of a water softener is to remove minerals (calcium and magnesium) from your water. In simple terms as your external water enters your home it passes through a silica filter that remove the minerals (through ion exchange) thereby "softening the water. The system then periodically back flushes the filter with a saline solution that flushes the minerals from the filter. The salt pellets should dissolve in the bottom of the salt tank creating a saline slurry for the back flush. The frequency of the back flush can usually be set on your softener and will typically run once or twice a week in the early morning. You may be regenerating more often than required.

My system is an on demand system and regenerates every 250 g of usage. I use about 15 lbs of salt per month and am in an area that is considered to have fairly hard water. Whats important to note is that a softener only removes minerals and may have no impact on odours or tastes that you may experience in your drinking water. For that you may require a charcoal or reverse osmosis system.

I am not an expert, but have had some first hand experience.