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Negative Dilute Drug Test: What It Means and What Happens Next

A negative-dilute result means the lab found no drugs at or above its cutoffs, but the urine was more watery than normal. It is not a positive result. Whether you have to test again depends on the rules that cover the test. For DOT-regulated jobs, federal rules decide. For a non-DOT test like Pact's $40 10-panel, the employer's or program's written policy decides. This guide explains how labs decide a specimen is dilute, what each version of the result means, and what to do next.

Updated October 24, 2026 · Checked against the official sources listed at the end

How a lab decides a specimen is dilute

Along with the drug test, the lab checks whether the urine looks like normal human urine. Quest calls this specimen validity testing. It measures pH, creatinine and specific gravity (when indicated), and tests for substances added to the urine. Quest's sheet lists this validity testing, which it calls TestSure, with Pact's panel (unit code 65190N).

Two numbers decide whether urine is dilute. Creatinine is a normal waste product that the kidneys clear into urine. Quest says normal human urine creatinine is at or above 20 mg/dL. Specific gravity measures how concentrated the urine is compared with water.

For DOT tests, 49 CFR 40.88 sets the limits. A specimen is dilute when creatinine is at least 2 mg/dL but below 20 mg/dL, and specific gravity is above 1.0010 but below 1.0030. Quest's definitions page uses the same idea: creatinine and specific gravity lower than expected for human urine.

Negative-dilute, positive-dilute and substituted

Negative-dilute: no drugs found at or above the cutoffs, and the urine was dilute. Under DOT rules, the lab reports this with the creatinine and specific gravity numbers (40.97). The MRO then reports to the employer that the result was dilute, and explains the employer's choices (40.155).
Positive-dilute: a drug was confirmed even though the urine was dilute. Under DOT rules, the employer treats it as a verified positive and must not order another test just because it was dilute (40.197(a)).
Substituted: much more extreme values that aren't consistent with human urine. Under 40.88(b), that means creatinine below 2 mg/dL with very low or very high specific gravity. This is a different finding from dilute, and it is treated far more seriously.

The DOT rule for negative-dilute results

Pact's online 10-panel is not a DOT test, but the DOT rule in 49 CFR 40.197 is the clearest written model. When the MRO reports a negative-dilute:

If creatinine was 2 to 5 mg/dL, the MRO directs an immediate recollection under direct observation, and the employer must do it.
If creatinine was above 5 mg/dL, the employer may, but is not required to, have the employee test again right away. That retest is not directly observed unless another rule calls for it.
The employer must treat all employees the same. It may set different policies for different test types, such as retesting pre-employment dilutes but not random ones, and must tell employees in advance.
The retest result, not the first one, is the result of record.
If the retest is also negative-dilute, the employer can't order another test because of dilution, except when the MRO directs an observed recollection.
Declining the retest counts as a refusal to test under DOT rules.

Non-DOT tests: the employer's policy decides

DOT rules don't govern non-DOT tests. For Pact's 10-panel, the employer or program decides whether to accept a negative-dilute or ask for a new test. Some states also have their own drug testing laws, so employers should check theirs.

If you are an employer, decide your rule before you test and put it in your written policy. Then apply it the same way to every applicant or employee. Our guide to starting employee drug testing covers writing the policy.

If you got a negative-dilute result

It is not a failed test. No drugs were found at or above the cutoffs.
Ask the employer or program whether they accept it or want a new test.
If they want a new test on a Pact order, call Pact at 901-666-6970 before you order again. Ask what the new test costs. Pact's sales are final, so the first order isn't refunded.
On the day of any test, follow the collector's instructions.
If you have a medical condition or take a medicine you think matters, tell the MRO if they call. This page isn't medical advice.

Invalid results are different

An invalid result means something in the specimen kept the lab from getting a valid drug result. Quest says all invalid results are automatically tested twice. Under DOT rules, the MRO talks with the person about medicines, and may cancel the test and require a new collection (40.159). Our guide to drug test results explains each result type.

Common questions

Is a negative dilute a failed drug test?

No. It means no drugs were found at or above the cutoffs, but the urine was more watery than normal. The employer or program decides whether a new test is needed.

Will I have to retake the test?

It depends. Under DOT rules, a retest is required when creatinine was 2 to 5 mg/dL and optional otherwise. For non-DOT tests like Pact's, the employer's written policy decides.

Does a retest cost money?

Ask Pact before you order again. Call 901-666-6970. Pact's online orders are final sale, so the first test isn't refunded.

What creatinine level is dilute?

Under 49 CFR 40.88, a specimen is dilute when creatinine is at least 2 mg/dL but below 20 mg/dL and specific gravity is above 1.0010 but below 1.0030.

What's the difference between dilute and substituted?

Dilute urine is watery but still consistent with human urine. Substituted means values so low or so far off that they aren't consistent with human urine (40.88(b)). The two are handled very differently.