Wisconsin Prosecutor wrote:
A couple points, the COLOR of urine is not something any tester takes into account. It may be a tipoff there is a problem, but test DO LOOK to dilution and you FAIL the test if there is a dilution of the urine.
What you call "dilution" a lab refers to as the "specific gravity" of urine. If there is too much water and not enough "salts" the specific gravity of the urine changes. If the SG goes below a certain number (often 1.003) the sample is not considered a valid sample which results in a failure to pass.
I see where you are coming from and I agree with what you are saying, but I would feel confident saying most testers just use a basic 5-tab test that simply involves placing a drop of the urine onto a dab that tests for the 5 most common drug types and that's it.