Water is pooling in my bathtub and not draining. How do I prevent pooling of water in corner or end of bathtub?

This is not a manufacturer defect or problem with the bathtub itself. The cause is usually that the tub is not level.  The water is pooling in the corner or one side because the bathtub is A) not level on all 4 corners B) doesn’t have the required mortar base installed correctly C) has an uneven subfloor or D) it was not installed properly according to the instructions.  To fix this problem you must re-install the bathtub, apply the correct amount of mortar base for the tub to rest in, and then level all 4 sides and corners of the bathtub prior to securing it to the wall or surrounding. Once the tub is secured, re-level again prior to the mortar base curing.