  However the allowed range of $\theta_{\odot}$ ($\theta_{12}$) did not change
much with the inclusion of the KamLAND results. In this paper we probe if
future data from KamLAND can increase the accuracy of the allowed range in
$\theta_{\odot}$ and conclude that even after 3 kton-year of statistics and
most optimistic error estimates, KamLAND {\it may} find it hard to
significantly improve the bounds on the mixing angle obtained from the solar
neutrino data. We discuss the $\theta_{12}$ sensitivity of the survival
probabilities in matter (vacuum) as is relevant for the solar (KamLAND)
experiments. We find that the presence of matter effects in the survival
probabilities for $^8B$ neutrinos give the solar neutrino experiments SK and
SNO an edge over KamLAND, as far as $\theta_{12}$ sensitivity is concerned,
particularly near maximal mixing. Among solar neutrino experiments we identify
SNO as the most promising candidate for constraining $\theta_{12}$ and make a
projected sensitivity test for the mixing angle by reducing the error in the
neutral current measurement at SNO. Finally we argue that the most accurate
bounds on $\theta_{12}$ can be achieved in a reactor experiment, if the
corresponding baseline and energy can be tuned to a minimum in the survival
probability. We propose a new reactor experiment which can give the value of
$\tan^2\theta_{12}$ to within 14%. We also discuss the future Borexino and
LowNu experiments.
