Salt and Laundry

Last Friday I made the claim that baking soda is a poor replacement for Super Wash Soda, and is not necessary to add to the laundry detergent because I don't have hard water.  But what about people who do have hard water?  Hard water contains dissolved calcium and magnesium.  It can precipitate out of hard water as scale, which builds up on the insides of your washing machine (and tea kettle and everything else), and hard water reduces soap's ability to lather, whether in the shower, sink, dishwasher or washing machine, and reacts with soap to form a sticky scum.  You can combat hard water in various ways, including filtering it by distillation or reverse osmosis, adding  powdered borax or washing soda (already contained in our home made detergent), or running it through a water softener (which implies salted water).  What if we just add salt to the laundry detergent mix?
All over the internet you can find recipes for homemade fabric softener crystals using kosher salt and Epsom salts, but these two items are not interchangeable.  Epsom salt is magnesium sulfate (MgSO₄ + 7H2O).  Hard water is caused by calcium and magnesium.  So by adding Epsom salt to your laundry you are making  your hard water even harder.  Hard water causes soap to be less effective, fades colors, and causes fabric to feel rough and scratchy.  Kosher salt (sodium chloride) is NaCl.  When dissolved in water, the sodium chloride framework disintegrates as the Na⁺ and Cl⁻ ions become surrounded by the polar water molecules.  It makes your detergent work even harder. Salt is proven effective against blood, gravy, grease, ink, and wine. It is also great at getting out set in stains. And what is even cheaper than Kosher salt? Regular table salt (it's just crushed into a different size flake).  Adding table salt to your home made detergent is the way to go if you have hard water! If you don't have hard water, you may still consider salt as a stain pretreatment.