One should, never use the water that has been used by another for bathing. One should always perform the Homa for propitiating the celestials, and recite the Savitri Mantras.
अन्यस्य चाप्यवस्नातं दूरतः परिवर्जयेत्॥ शान्तिहोमांश्च कुर्वीत सावित्राणि च धारयेत्।