Last updated : July 14, 2025
The urine drug test is still the number one choice for employers who drug test their employees. Sometimes drug users try to “beat” the company drug test thinking they can take in a large amount of fluids just before the test and it will mask any drug metabolites that are in their system. The test is likely to come back marked inconclusive with the reason being either a negative or positive dilute. That may not bode well for the employee.
A diluted urine sample immediately raises suspicion that someone is trying to mask drug use by drinking excessive amounts of liquid. A negative dilute result indicates that there were no drugs in the employee’s system at the time they provided a sample. However, due to the red flag raised by the diluted urine result, most employers require a second drug test. And some of them, Department of Transportation (DOT) included, stipulate that it must be observed.
If the second test proves the specimen is diluted, the employee likely loses their job.
When the drug test is inconclusive in combination with a positive dilute result, there is rarely a second chance and the employee is fired. That’s because even if the specimen was diluted the drug metabolites present in the system registered high enough to register positive for drug use. However, some companies offer employees a second chance and allow them to return to work after having completed a drug rehab program. If that’s the case, it is documented within the company’s drug-free policies and procedures before drug testing is implemented.
How can they tell urine is diluted?
Laboratory equipment has become far more sophisticated since the early days of drug testing when merely drinking excessive amounts of liquid would mask drug metabolites. Advancements in drug testing technology have caused the test to become far more efficient as well.
In addition, lab technicians are well-trained and look for things that would immediately raise a red flag. The color of the urine is one of those because diluted urine is lighter than an undiluted specimen.
Urine samples are routinely put through validity checks which include the following:
Urine creatinine check
Creatinine is a waste product produced by the muscles in the body. When creatine, an amino acid, is metabolized, creatinine is the result. It’s removed from the body when your kidneys produce urine. The amount of creatinine present indicates the urine concentration.
The normal creatinine range is between 20 and 400 milligrams per deciliter (mg/dL). Diluted urine yields a creatinine level some where between 2 and 20 mg/dL.
Specific gravity check
Another monitor for the concentration of urine is the specific gravity test. It compares the water content of the urine to the amount of substance in it. Normal urine has a specific gravity that falls between 1.002 and l.020. Diluted urine has a specific gravity between 1.001 and 1.003.
The actual drug tests
Part of the reason that drug tests are so accurate is because they are run through two separate tests. The first is called an immunoassay (IA) test. It detects the presence of drugs by using antibodies. It’s a “test strip” type of test that detects whether or not drugs are present.
If the result is positive the specimen is sent on for the gas chromatography-mass spectrometry test. During this test, a gas is added to the urine that interacts with the substances found there causing them to separate. This test not only confirms the positive drug result but determines the level of the drug as well.
Diluted urine doesn’t always indicate cheating
There are several reasons that someone’s urine is diluted.
They are as follows:
- It can happen accidentally, say someone slams an extra cup of coffee that morning, perhaps.
- Health-conscious people know that staying hydrated is important and it may be their common mode of operation.
- They may suffer from shy bladder syndrome which makes it incredibly hard, if not impossible, for them to urinate in public restrooms.
- If someone is taking diuretics, it increases the production of urine and can result in a diluted specimen. Some foods, like watermelon, coffee, and tea, are natural diuretics.
- The kidneys are responsible for making urine, if they aren’t working properly it could cause an imbalance resulting in dilution.
Filter out the negative dilutes
Handing out a list of guidelines can go a long way toward preventing inconclusive results due to a diluted urine sample.
The list could include:
- Asking that fluid intake be limited for several hours before the test.
- Mention avoiding diuretics, and list the foods that act as natural diuretics, on the day of the drug test.
- Schedule drug tests early in the morning, especially for workers who require frequent hydration.
Most employees don’t use drugs and the reminder to help them obtain a negative result sans the dilute factor will save them the possible embarrassment of raising a red flag and having to be retested. Moreover, drug tests aren’t cheap! If your company isn’t spending money on a second test to ensure peace of mind, you can use those funds for scaling your company to the next level!
