After leaving the bathroom, even if one used it for their personal use, one does not need to wash their hands three times from a cup. In a situation that one does not have water to wash and would like to recite Asher Yatzar, if they are expecting to find water and will not forget to recite the bracha it would be best to wait for the water and then recite bracha. However, if one is worried that they may forget, then they should wipe their hands on something and recite the bracha. If one stuck their hand into the bathroom, for example to switch off the lights or to close the door, one may be lenient and does not need to wash the hand that entered the bathroom.