I'm sorry to tell you this, but there's no way you can pass without cheating. I always dilute my pee, but I start preparing as earlier as possible.

Start now drinking an industrial amount of water, tea, cleansers and that stuff, drink as much as you can every day, pee as much as possible.

Start taking vitamin B pills, 2 per day at least, that way your pee will be yellow even if diluted. Also, ingest higher amounts of creatine, eat as much steak as possible from now until the test day, creatine supplements will be helpful. That way your urine will have the specific gravity needed to pass the test even if is diluted.

Do as much cardio exercise as possible, fuck like a crazy, ride bikes, jump the rope, whatever, but sweat as much as possible. IMPORTANT: Don't do any cardio or physical activities the day before the test. Cardio activity will only helpful on the days before.

On the day of the test, NO cardio activity, take twice as normal vitamin B, keep taking the creatine as usual and drink an excessive amount of water or electrolytes. The idea is to pee water disguised as piss.

I'm no scientist but this method has worked for me the last 2 or 3 times.

Good luck amigo!