Drug tests are a part of most new job opportunities. Prospective hires know it might be coming, and current employees should be aware that random drug tests are always a possibility. Most employers use a standard five-panel drug test that screens for the five most common street drugs: marijuana, cocaine, opiates, amphetamines (meth, speed, ecstasy), and phencyclidine. With urine drug testing, there's something called a dilute test result. Let's talk about what this means.
What Causes a Negative Dilute Drug Test?
If an employee provides urine for a drug test and the specimen comes back dilute, it means that the person drank too much water prior to the test and literally diluted their urine. It could also mean they physically poured water into their urine sample before turning it in.
Of course, there's a way to measure the sample to confirm that it's indeed dilute. If the specimen has a creatinine of more than 5 mg/dL or less than 20 g/dL, and a specific gravity of less than 1.0010 or greater than 1.0200, it's considered a dilute specimen. Tests for creatinine and specific gravity are routinely run on urine samples, so labs know to look out for this.
There are two types of dilute drug tests. A positive dilute always means that you tested positive for an illegal substance, regardless of it being diluted. Despite the amount of water in the urine, the test still picked up on some kind of illegal drug. A negative dilute could mean one of two things. It could come back negative either because there truthfully are no illegal substances in the person's system, or because their urine was too dilute for the test to pick up on any.
Oftentimes, when an employer sees a negative dilute drug test result, they'll send the employee back for another test.
How Much Water Causes a Dilute Drug Test?
Science hasn't named one specific number — a precise amount of water to consume — that will end up as a dilute sample. The individual must have drunk an excessive amount of water in a short span of time before providing a specimen. The amount of water that will create a diluted sample likely varies from person to person. It might be a half gallon for one and a full gallon for another.
How Do You Avoid Diluted Urine?
If you're an employer, while you can't control what an applicant or employee does in the day or hours leading up to their drug test, as we've discussed, labs know what to look for to determine if urine is dilute, and, thus, a retest is needed.
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For individuals who think they might be tested, the most obvious piece of advice is to not drink copious amounts of water. Leading up to a drug test, you really don't need more than one full glass. In fact, it's ideal to provide your sample first thing in the morning before you go to the bathroom for the first time, so you're using the urine that was sitting in your bladder all night. But if you can't hold it that long and this option isn't feasible, then you should aim to empty your bladder a couple of hours before providing a specimen, taking care not to drink too much water in the hours before your test.
Additionally, you should avoid all diuretics until after you've finished providing a urine sample. Diuretics are any substances that promote urination. They don't only come in the form of over-the-counter pills. Other diuretics that you may not be aware of include green tea, black tea, parsley, and coffee — so you might want to hold off on your daily Starbucks run until later in the day.
It's important to remember that you don't need to be totally dehydrated and dying of thirst to avoid providing diluted urine. You can still drink water. Just limit it to only the amount you need to remain hydrated enough before your test.
Employee drug testing can get complicated sometimes, but we're here to make it easy. At US Drug Test Centers, we provide nationwide drug testing and drug policy solutions. Contact us today at 866-566-0261 to find a drug testing location near you.
Ashlee Arnold is one of the founders of US Drug Test Centers and is currently the Vice President. 
