I need advice on what to do, I keep failing drug tests.

I am trying to get a new job, but I keep failing drug tests for thc. The last time I smoked was late March/ early April. I drink at least a gallon of water a day and I’m very active. I am a bigger guy, I am 6’2” and 215. I really need some advice because this is killing me. I landed a job at a hospital but failed the drug test so I waited another two months to apply to another, which I also got, and also failed that drug test despite passing multiple at home brands including multi level tests.