For some reason, aspirin triggers a false negative on the common Assay-type urine screens. Myself and some others have been successful using a combination of dilution and aspirin to beat the drug test. this post will describe the method I use and I will leave it open for as long as it takes to work out some questions that may come up, then I will close it and make it sticky as a reference so that the specific method is easliy located. Here's what I have done: I don't dilute with water, I dilute with gatorade or pedialyte to which I add about 2 tablespoons of salt per quart (it tastes pretty bad) I also take a half dozen Tums or rolaids The reason I do the above is to consume extra salts and minerals in the hopes that as I dilute my urine I am keeping my specific gravity up in case it is checked-- a low specific gravity, which will occur if you flush you system with excess water and it is a means of detecting dilution. I always go to the lab within minutes of it opening-- i do this because there is usually only one or two people working right at the opening and they have to multi task getting the place open and dealing with their first cup of coffe and chit chat etc and they may be more likely to skip checking temps specific gravity etc. I always wear a suit and tie (I'm in my mid forties and want to appear to be mainstream, not alternate lifestyle) I take a creatine supplement bginnning two days prior and up to test time--creatine does not build up in yor system very much so it doesnt make sense to increase it for much more than a day or so prior. Test day. 2 hours prior to test I get up and urinate then drink: 1 quart of liquid, creatine supp. 3 aspirin, 4 rolaids 1hour prior 1 quart of liquid, 3 aspirin, b vitamin, 4 rolaids 1/2 hour prior 2 quarts liquid, 2 aspirin, 4 rolaids I uriniate as I feel the need throughout the process and right up to test time, there is no worry about being able to produce a sample, trust me your problem is going to be getting there without going in the car! I suggest that you test the process with water vitamin alone sometime prior to test day to determine at what point it is best to take the aspirin. Take it too late and it doesnt have time to show up. Take it too early and it flushes out before your test. Color is probably the least thing to worry about though givin thatmost people that drink a healthy amount of water have pretty clear urine. Well that's it. That has worked for me three times now. I am also a proponent of using home tests and doing dry runs to gain confidence that I am timing thing correctly and that it will work--nothing like that negative home test to eliminate some of the jitters.