  We use recent evidence of TeV neutrino events from NGC 1068, detected by the
IceCube experiment, to constrain the overdensity of relic neutrinos locally and
globally. Since these high-energy neutrinos have travelled long distances
through a sea of relic neutrinos, they could have undergone scattering,
altering their observed flux on Earth. Considering only Standard Model
interactions, we constrain the relic overdensity to be $\eta\leq 3.85 \times
10^8 (5.39 \times 10^{11})$ at the 95$\%$ confidence level for overdensities
with a radius of 14 Mpc (10 kpc), assuming the sum of neutrino masses saturates
the cosmological bound, $\sum_i m_i = 0.13$ eV. We demonstrate that this limit
improves with larger neutrino masses and how it depends on the scale of the
overdensity region.
