My Doctor gave me this formula for saline water in 1973 I have no idea what percentage it is but I have been using it with no problems. 1 pint of distilled water 1 teaspoon of Rock salt /ice cream salt non iodized salt. NOT table salt bring to a full rolling boil so the rock salt will dissolve. Make fresh daily. Hope this helps I was diagnosed with Bronchiectasis in 1973 after many years of not knowing why I was having so much trouble. I use the saline water in a warm mist nebulizer and an IPPB machine.