Nasal irrigation should only be performed with distilled water, water that has passed through a filter designed to capture bacteria and amoebas, or water that has been boiled and then allowed to cool to room temperature. Never use plain tap water, and don’t use water that is very hot or very cold.
The water should then be mixed into a saline solution. Many nasal irrigation devices come with a mix. But if you’d like to make one on your own, add a half-teaspoon of salt and a half-teaspoon of baking soda for every cup of water you’re going to use.