Summertime Sampling Success

Avoiding Common Pitfalls in Warm-Weather Testing

In this article: 

• Learn best practices for hot-weather sampling success
• Avoid common summer mistakes that delay lab results
• Tips for proper container use, PFAS protocol, and paperwork
• Prevent failed samples with easy field-ready guidance
• Watch 3 expert videos with step-by-step summer sampling tip

Summer brings longer days and often more sampling events—but it also brings higher risks of sample error. Rising temperatures, increased field activity, and longer transport windows can all lead to compromised data if best practices aren’t followed. At STL, we partner with water and wastewater professionals to ensure your warm-weather sampling goes off without a hitch.

Below are the most common summer sampling pitfalls—and how to avoid them.

1. Always Separate “Clean” vs. “Dirty” Matrix Samples

One of the most overlooked best practices is maintaining separation between clean and dirty matrix samples. Organize your coolers accordingly:

• Use separate coolers for potable (clean) vs. wastewater (dirty) samples.
• This prevents cross-contamination and protects sample integrity.
• If in doubt, treat your cooler like your sample—clean or dirty, but never both.

Be sure to disinfect your coolers with a chlorine based disinfectant, and let them air dry overnight to ensure it’s a clean environment for the next day’s work.

2. Bacteria Samples? Use Zip Locks—Always.

Bacteria samples are especially vulnerable during transport:

• Always place bacteria bottles in sealed zip-lock bags to prevent leakage.
• This protects your sample and other bottles from contamination.
• It’s a simple step that can prevent invalid results and resampling delays.

3. Avoid Gel Pens (Trust Us on This One)

You may love your gel pen—but your Chain of Custody form doesn’t.

• Gel ink runs when wet, making COCs illegible.
• Instead, use waterproof or ballpoint pens to ensure your documentation stays readable in all conditions.

4. Fill Out All Sections of the Chain of Custody (COC) Forms—Every Time

A partially completed COC can delay results:

• Missing information means your STL Project Manager has to track you down to confirm details, slowing the process.
• Be sure to complete:
  • Project Name
  • Sample IDs
  • Sample Dates/Times
  • Parameters requested
• A fully filled-out COC keeps your project on schedule.

5. Understand Your Hold Times—They Matter

Hold times are not suggestions—they’re rules. Especially in summer:

• Example: A non-potable eColi sample taken at 5:30 AM might miss the hold time window if transit is delayed because analysis must begin within 8 hours of collection.
• Know your method and test-specific hold times, and plan accordingly to avoid invalid results.

6. Don’t Overfill Containers

Overfilling your bottles can cause problems.

• Preservatives may get diluted or washed out, compromising the sample.
• Always follow fill lines and sampling instructions to preserve chemistry and compliance.

7. Double-Glove for PFAS Sampling

PFAS is notoriously sensitive:

• Always wear two layers of gloves to prevent contamination from personal care products or gear.
• Avoid using waterproof boots with fluoropolymer coatings and never handle PFAS containers without a clean glove layer.

8. Store Bottles With Acid Upright

Leaky bottles = ruined coolers and invalid samples.

• Keep any bottles containing acid upright when in storage and in the cooler.
• Use dividers or secure slots to minimize tipping during transport.

Partner with STL for a Smoother Summer

When the weather heats up, small mistakes can lead to big delays. At STL, we’re more than your lab—we’re your partner in protecting public health and compliance. With expert Project Managers, flexible logistics, and quick response times, we’re here to help you get it right the first time.

Need support or field guidance? Contact us.

Suburban Testing Labs: Trusted. Reliable. Local.

Want to learn more about our testing capabilities or how we can support your operations? Contact us today for a personalized consultation or quotation.  Email us at sales@suburbantestinglabs.com or fill out our contact form for a quick response.