Actually, the water is neither acidic nor basic. It's neutral. [H+][OH-]=Kw. The pH ithe negative log of the [H+]. Thus, at Kw=1*10^-14, the H+ OH- concentrations would both be 1*10^-7, and the pH and pOH would be 7. In our case, the Kw is 5*10^-14 and thus the [H+] and [OH-] would each be 2.2*10^-7, making the pH and the pOH both 6.65.
Remember, acidic means that there is more H+ than OH-. If they are equivalent, it is neutral no matter what the pH is. pH=7 is neutral only when Kw=1*10-14.