Hi there ~
I understand your concerns. Cannabis can stay in your system from 2-4 months depending on the length and amount of usage. You will not be able to "wash out" marijuana by drinking a lot of water so please avoid doing this. If you have not symptoms it might be as well to wait the time and not use cannabis in the meantime. If you do have symptoms; please consult a psychiatrist
who specializes in substance use disorders.
I hope this helps. Take care and have a lovely day!