I recently added this receptacle to my bathroom because I am putting a vanity here that has a built-in power bar and previously the only receptacle in the bathroom was the GFCI outlet at the top of the image. I put the new receptacle low to the ground because I need to be able to fit the plug for the vanity underneath the vanity's feet, or else the vanity wouldn't be able to be pushed right up into the corner. The new receptacle is GFCI protected by the aforementioned GFCI receptacle, and while it is only a 15 amp receptacle, it is wired to the GFCI outlet with 12/2 wire which leads back to a 20 amp breaker.
In all my research, I didn't find any code requirements for minimum outlet height or orientation, but my friend saw my work and said that flooding could pose a hazard and now I am questioning myself.
I am in the United States where NEC is the applicable code.