Can You Mix Water into a Urine Sample for a Drug Test?

No matter who you are or where you come from, everyone has the same goal when it comes to drug tests: To pass. Most people will likely have no problem passing. But others will have to go to great lengths to ensure their urine samples pass muster—and if you are reading this article, chances are you fall into the latter category.

One of the most common strategies is to dilute the urine sample. If individuals drink large amounts of liquid, the hope is the THC or whatever flag-worthy substance becomes undetectable.

The real question is whether or not diluting your urine sample works. Can you add water to negate a positive result?

The following questions and answers will provide you the insight you need to understand the pros and cons of dilution.

What Substances Are Tested in a Screening?

A standard five-panel drug screening is often the test of choice for substance abuse. This test means the lab workers analyzing the sample will look for substances such as marijuana, opiates, cocaine, and methamphetamine, to name a few.

Some private employers may choose a more thorough testing procedure, and also try to detect things like steroids and ecstasy.

women in scrubs signing okay and hold urine sample in opposite hand — Portrait of young pretty brunette positive woman doctor standing in office with bottle of urine in her hands in purple uniform

People who do not use any of the previously mentioned substances should have no reason to fret. But if you use a specific substance and are wondering if the test will look for it, the general rule of thumb is that when in doubt, expect your substance of choice to be in the screening.

How Long Does a Substance Stay in Your Body?

Unfortunately, the short answer is: It depends. The long answer is more complex and relies on a variety of factors. The Drug and Alcohol Testing Industry Association does have a handy chart for how long certain drugs are detectable.

The lifespan of a substance depends on the individual who consumed it, their lifestyle, and their frequency of use. For instance, regularly smoking marijuana will extend the likelihood of detection, as the amount of THC in the body increases over time.

And while we are focusing solely on urine tests here, the detectability also depends on which screening is being used; others include the use of hair, saliva, or blood samples.

The most influential factor in detectability is one’s lifestyle. People with higher BMI and poor diet are more likely to have a substance linger in the body.

Active individuals who drink a lot of water and eat well have less mass to store chemical substances; they also usually have a higher metabolism to process them, so they are less likely to test positive for comparable use.

What Is Dilution?

Dilution is when you decrease the concentration of a solute (a chemical substance in this case) within a solution. This process can be done through various means, though adding water is most simple and straightforward.

Adding water to the solution lowers the total percent of solute in the whole.

Should I Add Water to My Urine to Pass a Screening?

This is the million-dollar question. And the answer is: No, you really shouldn’t. Technically, you can add water—but we strongly advise against doing that.

Adding water is a bad idea because of the test for specific gravity. Specific gravity makes sure your urine resembles urine and not water.

A standard measure for pee will fall between 1.001 and 1.003, while water will register a perfect 1.000.

If your urine falls outside those two figures, it will be declared a “diluted urine drug test,” rendering it invalid, and you will have to perform the screening again.

How Much Water Can Cause a Diluted Urine?

There are no hard and fast rules when it comes to exactly how much water it takes to dilute a urine sample to the point of voiding the test. Drinking a half-gallon may be enough to trigger a diluted test depending on the size of the individual.

The best advice we can give is not to drink an excessive amount of water before the test, as you may incur adverse health effects.

That said, some people might want to deliberately submit a diluted sample as a way to buy more time. The idea is that having to retake the test at a later date will give them more time to detoxify their body. We do not advocate this strategy.

This method also will not work for on-site urine tests, which have immediate results and will require the provider to wait in the immediate area until they can provide another sample.

How Do You Avoid Diluted Urine?

The most important piece of advice is to avoid drinking an excessive amount of liquid, especially before you have to take the drug test.

A glass or two of water on the day of the drug screening should be ample when it comes to providing a testable sample.

If you do have to urinate before the test, try to do so a few hours before, so you will be able to pee again later.

Avoiding diuretics will also go a long way toward preventing diluted samples. Diuretics, such as tea and coffee, may result in untestable urine because there is too little solute present. Try to hold off caffeine fix until later in the day, or if you have to have it, limit yourself to one cup.

If you are certain to fail the test, you may want to consider an outside source. Using synthetic urine—which resembles the characteristics of real pee—is a foolproof option when it comes to dilution. High-grade synthetic urine may be a particularly appealing option if you do not have to take the drug test on-site.

Final Thoughts

Drug tests are a common way for employers to check for illegal drug use among their employees. As urine tests become increasingly accurate, people who regularly use drugs need to seek alternatives to get around the system.

These methods include such questionable tactics as diluting their urine samples with water, though this practice is unreliable at best.

While you can dilute the sample, it does not guarantee that certain drugs will not be detected, nor does it prevent a provider from performing the test again, immediately.

There are many better options than dilution when it comes to detoxing. A healthy diet with regular exercise and abstinence from chemicals and toxins provides the best chances of success.