A simple calculation can show how small a fraction of water molecules is dissociated. A concentration of 1.0 x 10^-7 moles of H⁺ per liter of water means that 1.0 x 10^-7 moles of H₂O has dissociated per 55.5 moles of water, or one part in 0.56 x 10^-9.

Approximately two water molecules out of every billion are dissociated into H⁺ and OH^- ions. The animation shows what a tiny percentage that actually is...