The dissociation of water is an equilibrium reaction in which one water molecule donates its proton to another water molecule. The dissociation of water is a dinamic equilibrium.
https://chem.libretexts.org/Bookshelves/Introductory_Chemistry/Introduction_to_General_Chemistry_(Malik)/06%3A_Acids_and_bases/6.05%3A_Dissociation_of_water