  Neutrinos in the cosmic ray flux with energies near 1 EeV and above are
detectable with the Surface Detector array of the Pierre Auger Observatory. We
report here on searches through Auger data from 1 January 2004 until 20 June
2013. No neutrino candidates were found, yielding a limit to the diffuse flux
of ultra-high energy neutrinos that challenges the Waxman-Bahcall bound
predictions. Neutrino identification is attempted using the broad
time-structure of the signals expected in the SD stations, and is efficiently
done for neutrinos of all flavors interacting in the atmosphere at large zenith
angles, as well as for "Earth-skimming" neutrino interactions in the case of
tau neutrinos. In this paper the searches for downward-going neutrinos in the
zenith angle bins $60^\circ-75^\circ$ and $75^\circ-90^\circ$ as well as for
upward-going neutrinos, are combined to give a single limit. The $90\%$ C.L.
single-flavor limit to the diffuse flux of ultra-high energy neutrinos with an
$E^{-2}$ spectrum in the energy range $1.0 \times 10^{17}$ eV - $2.5 \times
10^{19}$ eV is $E_\nu^2 dN_\nu/dE_\nu < 6.4 \times 10^{-9}~ {\rm GeV~ cm^{-2}~
s^{-1}~ sr^{-1}}$.
