Field Test · April 14, 2026
Do tea bags leak microplastics? I tested 3 brands.
Short version: yes. I brewed three different tea bag brands this morning and ran each cup through our at-home kit. Every filter came back covered in pink dots. Every pink dot is a piece of plastic. You can count them without a microscope.
30-second walkthrough. Brew → filter → blue light.
The test
Three mugs. Three tea bags. Boiling water. A premium pyramid-mesh brand, a standard paper bag, and an “organic” supermarket blend. I pulled the bags after a full steep, let each cup cool, and ran them through the kit one at a time. I also ran a blank (just clean water from the tap) to make sure the signal wasn't coming from the kit itself.
The method takes about five minutes per cup:
Digest
A thirty-minute solution that breaks down tea leaves and tannins so they don't clog the filter.
Stain
Nile Red fluorescent dye. It binds to plastic. It cannot stick to minerals, dissolved salts, or tea residue.
Filter
Vacuum the stained sample through the PTFE disc in the kit. Anything the dye attached to gets trapped on the filter face.
Glow
Point the blue LED at the disc. Plastic glows bright pink. Everything else stays dark.
Full method writeup with references: How It Works.
What I saw
I laid the three tea filters next to the blank on a black mat and shined the light.
The blank was dark. The three tea filters were not. All three are covered in pink dots. You can see them from the other side of the table. Pyramid mesh did it. Paper bag did it. “Organic” did it. No brand was clean.
My wife walked in, and without me saying anything, she picked out the blank immediately. It was the one that wasn't glowing.
The bottom line
Every brand I brewed had pink dots on the filter. You don't have to trust me. You can run the same test, in your own cup, tonight, for $50.
What to do about it
A few easy switches if you drink tea every day:
- Loose leaf in a stainless steel infuser. No bag, no heat-sealed plastic, nothing to shed.
- 100% cellulose bags, explicitly advertised as plastic-free. Many “natural” and “organic” bags are still heat-sealed with polypropylene film. Read the box.
- Glass or stainless vessels. Plastic-lined travel mugs and plastic infuser baskets are worse than a plain ceramic cup.
Or keep drinking what you drink. You'll at least know what's in it.
The rest of what the kit runs
Tea is one sample. The same method runs on anything you drink or brew:
- Bottled water, your fridge dispenser, your filter pitcher (before and after)
- Brewed coffee, cold brew, takeaway cups
- Your shower head, your gym bottle, the “filtered” water at a hotel
- Tap water, side-by-side against any of the above
Each kit does two tests, so you can compare any two sources side by side.