Will it harm to water house plants with water that runs through a water softner that uses salt.?

I wouldn't water with softened water.

Will it harm to water house plants with water that runs through a water softner that uses salt.?
not usually. it can leave a residue of sorts though. the soil will get a white crusty coating on it sometimes. usually, cold water from a kitchen sink is not run through a water softener, so use that.
Reply:No, it doesn't add salt to the water. The salt collects iron and other deposits, your waters not salty when you drink it right?