you very well may fail your drugs test, it can take up to a month for all traces to leave your system, a minimum of 2-3 days is usually required, but more than likely at least a week for occasional users.
Drink water, but not too much as they can reject samples that are too pale...knowing that you purposely diluted your urine.
if they suspect you have used, they may take a blood test which will most definitely show that you are using.