I have a water softener and filtration system that once or twice a month flushes/cleans itself by running 50 gallons or so of clean water over the softener balls. I think this is standard with most softeners.

I use potassium chloride in my softener, not sodium.

I would like to use the collected flush water to water a vegetable garden.

Problem is that when I tried this, many but not all the vegetables turned brown and/or died. I assume its due to the potassium chloride in the flush water.

Any ideas? I am a novice gardener, and my water supply is very low during summer months and I feel really bad everytime the softener flushes itself.