What status, if any, does a washing cup retain? May i use the same cup that i use for netilas yadayim or negel vasser in the morning to drink from? Or may i use it to pour water from the sink into a percolator?
Thank you for your question.
Yes, you may. However, the Gemara Horayos 13b writes that drinking water leftover from washing causes forgetfulness. Therefore you should spill out the remaining water in the cup before you use the cup for drinking purposes, e.g. using it to pour water into a percolator.
All the best
See Teshuvas Ve’hanhagoes 2:114 regarding this issue, and in the name of the Avnei Nezer that drinking water left over from netilas yadayim causes one to have heretical thoughts.