do you think this means there is something missing in her diet? I have heard of dogs eating poo (she does that too) but not drinking wee. She is around 24 weeks old
Does she do it indoors or out? If she is housetrained and goes outside then drinks it, you need to be with her to distract her as soon as she has gone. If she is still weeing indoors you need to go back to basics and let her out more often, then stay with her till she has done it. Either way although it won't harm her, its a bad habit that you need to get her out of, especially if she has access to anywhere another dog has gone.