  Transition intensities for small molecules such as water and CO$_2$ can now
be computed with such high accuracy that they are being used to systematically
replace measurements in standard databases. These calculations use high
accuracy ab initio dipole moment surfaces and wavefunctions from
spectroscopically-determined potential energy surfaces. Here an extra high
accuracy potential energy surface (PES) of the water molecule (\hato) is
produced starting from an ab initio PES which is then refined to empirical
rovibrational energy levels. Variational nuclear motion calculations using this
PES reproduce the fitted energy levels with a standard deviation of 0.011 \cm,
approximately three times their stated uncertainty. Use of wavefunctions
computed with this refined PES is found to improve the predicted transition
intensities for selected (problematic) transitions. A new room temperature line
list for H2(16)O is presented. It is suggested that the associated set of line
intensities is the most accurate available to date for this species.
