Remember that in water, the concentration of hydronium ions, or H⁺, will equal the concentration of hydroxide ions. That is [H⁺] = [OH⁻].
Remember that Kw = [H⁺][OH⁻] for water and if [H⁺] and [OH⁻] are both equal, we can easily solve for them by taking the square root of Kw.
[H⁺] = sqrt(1.219*10^-14) = 1.104*10^-7
and remember that pH = -log[H⁺] = -log(1.104*10^-7) = 6.9570
(The rules for sig figs are that if you take the log of a number with x significant figures, then the result should have x significant decimal places.)
The pH of water is 6.9570
