[header] How to extract your dna [title] Create a mouth rinse. [step] To extract your dna from saliva, you'll need to create a mouth rinse first. You'll be mixing salt into water, because salt provides a rough, granular texture to help collect cells from your mouth. 
It also helps protect the negative phosphate ends of your dna, allowing it to precipitate out of the saliva. [substeps] Mix one tablespoon of salt into 500 milliliters of clean drinking water.