OK I'll go look up some numbers...
My actual cost to operate my softener is around $4 per regeneration, once per day average year round. (Yes that can mean 4 or 5 regens on those weekends we all pray for.)
Fleck 9000 dual reciprocating unit, 68,000 grain tanks.
Note: small rural self serve, all water is softened.
Thats a quickie calculation based on my fully loaded actual water + sewer cost, measured water hardness (25 grains), daily average water usage, actual cost of salt, estimating 120 gallons per regen. I'd have to check, but I think I set mine to use the recommended 75% of resin capacity.
I've always intended to have the rinse & washdown water bypass the softener, but for the savings I just never get around to it. I suppose that if I saved half of my softening costs, that would be maybe $5-600 /year? OK soapy, maybe I should get around to it
Yeah, with an IBA I'd definitely bypass the softener for the rinse cycles.