A drug test is only as reliable as the sample. People who expect to fail sometimes dilute, substitute or tamper with their urine. The good news: most attempts can be caught with a temperature strip, a few quick checks and a careful collection process.
The three most common tricks
- Dilution: drinking large amounts of water before the test, or adding water to the sample, to push levels below the cutoff.
- Substitution: handing in someone else's urine or synthetic urine instead of their own.
- Adulteration: adding something to the sample, such as bleach, soap or products sold to "beat" drug tests, to interfere with the result.
1. Check the temperature within 4 minutes
Fresh urine leaves the body at body temperature. A sample should read between 90 and 100°F (32 to 38°C) within 4 minutes of collection. A reading outside that range is a red flag for substitution. Most of our drug test cups have a built-in temperature strip on the side.
2. Look at the sample
- Very clear, pale urine can mean dilution.
- Unusual color, foam, cloudiness or a smell like bleach or soap can mean adulteration.
- A very small amount, or a sample that is cold to the touch, is worth a closer look.
3. Use adulterant checks
| Check | What it catches | Red flag |
|---|---|---|
| Specific gravity (S.G.) | Dilution and substitution | Very low specific gravity, close to water |
| Creatinine (CRE) | Dilution and synthetic urine | Creatinine below 20 mg/dL suggests a dilute sample |
| pH | Adulteration | pH below 4.5 or 9 and above |
Our 20 panel drug test cup includes pH, specific gravity and creatinine checks alongside 19 drug tests. Read the pads against the color chart on the label.
4. Set up the collection area
- Ask the donor to leave coats, bags and bulky items outside the bathroom.
- Turn off or tape the sink and add blue dye to the toilet water so it cannot be used to dilute the sample.
- Remove soap, cleaners and other products from the room.
- Keep the wait short and do not allow drinks between the notice and the collection.
- Test at random times, so there is less time to prepare a substitute.
- Where your policy allows, use a same-gender observed collection.
What to do if you suspect tampering
Document what you saw, including the temperature reading and the time. Many programs treat a failed temperature or adulterant check the same as a refusal to test, and require an immediate, observed retest. Put this in your written testing policy so it is applied the same way every time. See our guides for sober living homes and employers.
Ordering for a house, program or company?
Volume pricing starts at 25 units and gets better at 50, 75 and 100. For standing orders or 500+ units, call (866) 407-2832 or email sales@drugtestsdirect.com for a quote.
Request a Bulk QuoteFrequently asked questions
What temperature should a urine sample be?
Between 90 and 100°F (32 to 38°C), checked within 4 minutes of collection.
Can you tell if urine is diluted?
Often, yes. Very pale color, low specific gravity and low creatinine are signs of dilution. Tests with S.G. and CRE checks help confirm it.
Do your drug test cups detect fake urine?
Our cups' temperature strips help catch substituted samples, and the 20 panel cup adds pH, specific gravity and creatinine checks.
What should I do with a sample that fails the temperature check?
Follow your written policy. Many programs require an immediate observed retest.
Instant urine tests give preliminary results. Confirm any preliminary positive with a laboratory test (such as GC/MS) before taking action. Always follow the package insert.