My softener uses potassium chloride and it seems to affect the taste of the water when it recharges. The bad taste would come and go after a few days time. I put it on bypass and the bad taste has gone away. I put a small piece of the potassium chloride in a glass of water to let it dissolve and sampled it and it seems to be the culprit. Do I need a new softener?
I have a water softener unit that would put a bad taste in the water after the regeneration cycle, although I could flush it out in a few minutes versus a couple of days. I fixed it by replacing the valve mechanism at the top of the tank - the valves had become clogged with sediment and weren't closing properly, thereby allowing the salt-infused water to enter the drinking water pipes. Replacing the valve system cleared up the problem for me.
I found the product I needed and instructions by searching for the water softener model on the internet. This may be an easier and less expensive fix than replacing the whole unit.
I agree with Ed on PCR, check for build-up problems. However for me, losing the water softener after it rotted out was the real & best answer. My water softener only "worked" for its 1st 5-years, after that all the charm & benefit was gone regardless of how often I forced a backwash or had the charcoal replaced. I went to a Pelican whole house filtration system, because they were the best designed, cheapest & longest lasting that I could determine at the time.
I never liked the backwashing & salt nonsense of mostly just treating the water like most water softeners do. I was never impressed with the amount of carbon filtration that was in mine. But, actually removing the minerals entirely not only makes the most sense, but also not adding anything else to the water makes for vastly much better water overall. I'll never go back to a water softener.