  The probability of nuclear transitions $p+p+{}^{16}{O} \, \rightarrow \,
{}^{18}{Ne}\, (4.522,1^-)$ in molecular water is estimated. Due to the
practically exact agreement of the energy of the $Ne$ resonance and of the
$p+p+{}^{16}{O}$ threshold, the transition probability is found to be
considerably enhanced. This indicates the possibility of nuclear fusion in
rotationally excited $H_2O$ molecules in the state $1^-$.
