Vastu says, if the over-head water tank is situated in the North then you will suffer from monetary losses always, because it is a load on the head. The load is always carried on the back according to vastu; hence, the preferable direction to keep the water tank direction is east.
If the water tank is kept in north-east direction, you will suffer from monetary losses, loans won’t be recovered, fixed salary will also reduce, etc. Hence, south-west, west and south are the best directions for keeping the water tank. North-west and south-east should be the secondary options.