In Figure , we see that the minimum-energy sites correspond to local maxima in ⟨⃗ µ z ⟩, indicating an stronger alignment of the water dipoles along the z-axis. The sum of these dipoles over the length of the pore yields ⟨⃗ µ z ⟩dz = 11.0±1.5 D. This is consistent with a previous MD study on an open KcsA channel that revealed a water dipole in the selectivity filter region of ∼11 Debye. Since water alignment informs on the intensity of the electric field in the pore, our results suggests that the electric field generated by the residues of Na v 1.7 is non-uniform, with enhanced magnitude at Na + binding sites. The relaxation time of the pore water dipoles can be calculated with the orientational autocorrelation function, C(t) (see Methods). In Figure , we show C(t) for each conformation, the ensemble average and its fit to Equation 4 (R 2 = 0.991). We find A = 0.8, B = 0.2, τ A = 18.1 ps and τ B = 610.1 ps. For comparison, waters in the first solvation shell of Na + were shown to relax on the timescales of 25 ps (orientational dynamics) and 160 ps (tumbling motions). Meanwhile, experimental and MD studies found two relaxation time constants for bulk water, the larger between 7 and 8.5 ps, and the smallest between 0.2 and 1.5 ps. The much longer relaxation time we compute for pore waters in Na v 1.7 suggests that the water molecules interact with the residues of the channel, causing retardation in their orientational motion, as previously reported in other protein environments. In Figure , we show the dipole orientation crosscorrelation functions between pore water pairs. The flat-lined C cross (t) indicates that water dipole orientation does not depend on other waters. This further validates our calculations that shows that protein residues are the main contributors to the electric field in the pore, therefore the main factor governing water relaxation dynamics.