  The network connectivity in liquid water is revised in terms of electronic
signatures of hydrogen bonds (HBs) instead of geometric criteria, in view of
recent X-ray absorption studies. The analysis is based on ab initio
molecular-dynamics simulations at ambient conditions. Even if instantaneous
thread-like structures are observed in the electronic network, they
continuously reshape in oscillations reminiscent of the r and t modes in ice
(tau~170 fs). However, two water molecules initially joint by a HB remain
effectively bound over many periods regardless of its electronic signature.
