Most plants cannot tolerate high amounts of salt. The sodium in softened water actually interferes with the water balance in the plants and can kill plants by “fooling” them into thinking they have taken up more water than they have. Softened water essentially causes the plants in your garden to die of thirst.

Will softened water kill grass?

Why isn't your softened water good for the lawn? Softened water is treated with salt to help remove the minerals from hard water. ... It's unlikely that your water softener salt will kill your grass, especially not by using it to water occasionally. But prolonged use of soft water just isn't ideal for your garden.

Why can't you drink softened water?

Softened water is considered safe to drink in the majority of cases. ... In softened water, the sodium level increases. Sodium is not the same as salt (sodium chloride). The Drinking Water Inspectorate (DWI) says that water with a sodium content of up to 200ppm is safe to drink.