I am no expert, but I would say no as that won't get to the internal parts where the water is flowing though. Why not look in to a whole house water softner.

Nancy0852,

I posted the reply below to your first (same) post of this question in the Laundry Room forum. No. Simply adding salt to a washing machine or dishwasher won't do anything other than create salty wash or rinse water.

Machines (dishwashers) that take salt in fact have a built-in water softener mechanism ... a mini version of whole-house softeners. Salt is never injected into the washing/rinsing water. It's used to recharge the resin bed that removes hardness by exchanging calcium ions in the hard water for sodium ions (a chemical process). The recharge process involves backflushing the resin bed with salt water, then the solution is dumped to the drain.