  Young stars are known to show variability due to non-steady mass accretion
rate from their circumstellar disks. Accretion flares can produce strong
energetic irradiation and heating that may affect the disk in the planet
formation region, close to the central star. During an extreme accretion
outburst in the young star EX Lupi, the prototype of EXor variables, remarkable
changes in molecular gas emission from $\sim1$ AU in the disk have recently
been observed (Banzatti et al. 2012). Here, we focus on water vapor and explore
how it is affected by variable accretion luminosity in T Tauri stars. We
monitored a young highly variable solar-mass star, DR Tau, using simultaneously
two high/medium-resolution ESO-VLT spectrographs: VISIR at 12.4 $\mu$m to
observe water lines from the disk, and X-shooter covering from 0.3 to 2.5
$\mu$m to constrain the stellar accretion. Three epochs spanning timescales
from several days to several weeks were obtained. Accretion luminosity was
estimated to change within a factor $\sim2$, and no change in water emission
was detected at a significant level. In comparison to EX Lupi and EXor
outbursts, DR Tau suggests that the less long-lived and weaker variability
phenomena typical of T Tauri stars may leave water at planet-forming radii in
the disk mostly unaffected. We propose that these systems may provide evidence
for two processes that act over different timescales: UV photochemistry in the
disk atmosphere (faster) and heating of the disk deeper layers (slower).
