However the Jews of old did it, the tunnel is still there, and the waters of the spring still flow through it. For the small cost of an entry ticket, tourists and pilgrims can follow this underground stream to the Pool of Siloam. It is somewhat surprising that visitors are left to do this unsupervised. The tunnel gets quite narrow at some points, and it could be quite problematic if someone had a panic attack or some other accident somewhere in the middle, 250m from any help. Perhaps they rely on the fact that there are always people passing through.
Pool of Siloam
(rather smaller than in Biblical times)