The reservoir tank represents the elements of water in FengShui when situated at the right place will bring good wealth luck. The army camp represents fire due to its aggressive nature.
If your house is a terrace house which have a reservoir on one side (for example on a hill top) and at your back of the house is another hill where an army camp is situated and some times you might even hear live ammunition being fired in their firing range. These might raise some sound of echoes and a nuisance.
In FengShui theory, the element of water should subdue the element of fire; but remember no matters water is the winner or loser, any fight between two elements is bad; the more fierce the battle the more severe is the effect. If you house stay in line like the above house which stay in line between the two forces, there is a struggle between the two elements. Therefore, the situation is very unfavorable to the house’s occupants. They will have continuous money and health problem. The chances of accidents are much higher.
If you are staying in such environment, the best thing to do is look for another more auspicious place to stay.