Question

why does the water forms the spherical droplet

Answer 1

hey mate..

Liquid drop always  assume spherical in shape because drop always tends to acquire minimum surface area due to surface tension, and for a given volume, the surface area of sphere is minimum. 

Answer 2

water has more cohesive force than adhesive and so the water molecules always tend to move inwards thus forming a spherical shape.
Surface tension causes molecules to move inwards and water has the highest surface tension among all other available liquids.