As BRY2K says, there doesn't seem to be a reference to any mythological Greek characters who lived in a tub.
However, the philosopher Diogenes was renowned for living in a public tub or water trough as an expression of his ascetic principles.
Once in Athens, Diogenes famously took a tub, or a pithos, for an abode. In Lives of Eminent Philosophers, it is reported that Diogenes “had written to some one to try and procure a cottage for him. When this man was a long time about it, he took for his abode the tub in the Metroön, as he himself explains in his letters” (Diogenes Laertius, Book 6, Chapter 23). Apparently Diogenes discovered that he had no need for conventional shelter or any other “dainties” from having watched a mouse. The lesson the mouse teaches is that he is capable of adapting himself to any circumstance. This adaptability is the origin of Diogenes’ legendary askçsis, or training.
http://www.iep.utm.edu/d/diogsino.htm
There is also a legend that Alexander the Great, who admired Diogenes' philosophy, upon hearing of his circumstances, travelled to visit him and asked if there was anything he could do to help him. Diogenes reportedly replied, "Yes, you can stand aside. You're blocking my sunlight."