  Attractive bonding interactions between molecules typically have inherent
conservation laws which influence the statistical properties of such systems in
terms of corresponding sum rules. We considered lattice water as an example and
enunciated the consequences of the sum rule through a general computational
procedure called "Molecular mean field" theory. Fluctuations about mean field
are computed and many of the liquid properties have been deduced and compared
with Monte Carlo simulation, molecular dynamics and experimental results. Large
correlation lengths are seen to be a consequence of the sum rule in liquid
phase. Long range Coulomb interactions are shown to have minor effects on our
results.
