How It Works
How You Test Your Water
The kit uses Nile Red fluorescence staining — developed in academic labs and validated in peer-reviewed research. We didn't invent this science. We packaged it so anyone can run it at home.
Based on: Leonard et al., “Smartphone-enabled rapid quantification of microplastics,” Journal of Hazardous Materials Letters, 2022. DOI: 10.1016/j.hazl.2022.100052
Collect your water samples
Use any glass container you have at home — a mason jar, a drinking glass, anything clean. Fill it with about 100 mL of water. Glass, not plastic — so the container can't contaminate what you're testing. The kit includes two complete tests so you can compare any two sources side-by-side.
Add the digestion solution
Pour in the clear solution included in the kit. This breaks down algae, biofilms, and other organic material that could interfere with your results. Wait 30 minutes for the digestion to work.
Add the Nile Red stain
Add the Nile Red stain — the fluorescent dye. It binds specifically to hydrophobic (water-repelling) particles, which includes virtually all common plastics. It physically cannot bind to minerals, salts, or dissolved solids. That's not a design choice — it's chemistry. Wait 30 minutes to 1 hour.
Filter your sample
Push the stained water through the included filter using the applicator. The filter traps everything the dye attached to while the water passes through.
Shine the blue light
Place the filter under the included blue LED light. Particles indicating microplastics glow bright pink against the filter background. You'll see them immediately with your own eyes — no microscope required.
Upload your photo
Take a photo of your filter and upload it to our system. Our imaging pipeline counts the particles, sizes them, and generates a report — including how your water compares to other homes we've analyzed.
Compare and interpret
More pink specks = more potential microplastics. Run the second test with filtered water and compare side-by-side. The difference tells you whether your filter is actually working. Your report includes a severity rating and context for what the numbers mean.
What You Get
- Particles indicating microplastics glowing pink on your filter — visible to the naked eye
- Clear before/after comparison if you test tap vs. filtered water
- Upload your photo and get a full analysis — particle count, size distribution, and severity rating
- See how your water compares to other homes in our database
- Two complete tests per kit
What We Detect
- Microplastic particles ≥10 µm (width of a red blood cell)
- All common polymers: polyethylene, polypropylene, nylon, PET, polystyrene
- Fibers, fragments, and films
What We Don't
- Nanoplastics (<10 µm) — no consumer test does this
- Exact polymer ID (PE vs PP) — that's the $800 test
- Certain hydrophilic plastics (rare in drinking water)
We're transparent about this because no test is perfect. The $800+ FTIR/Raman tests can identify polymer types, but they detect the same size range of particles. The question is whether you need an $800 answer or a $50 one you can run at home.
Quality Controls
Procedural blanks on every batch
A control sample with no water, processed identically to yours. Catches any lab contamination. Blank counts are subtracted from your results.
Locked protocol
Every sample follows a standardized, locked procedure. Same dilution ratios, same timing, same imaging conditions. Consistency is how you get trustworthy data across thousands of tests.
Glass-only contact
Samples only touch glass and non-plastic materials. No plastic containers, no plastic tubing. The container can't contaminate the sample.
Every sample public
Every test result and its raw image gets posted to the public map. Anyone can look at a sample and tell us if something looks wrong.
Validation Roadmap
We don't claim to be done. We claim to be transparent about what we're testing right now. Big lab companies tell you everything is finished. We're showing you the work in progress, because the work is the trust.
Peer-reviewed detection method
Nile Red fluorescence imaging, based on the protocol described in Leonard et al. 2022 (Journal of Hazardous Materials Letters). We adapted the published method — we didn't invent it, and we're not affiliated with the authors.
Procedural blanks on every batch
Control samples with no water, processed identically. Contamination gets caught and subtracted before your number ships.
Spike-recovery calibration curve
Running known concentrations of polyethylene reference particles (0, 10, 100, 1,000 per 100 mL) through the kit pipeline to publish a kit-vs-known regression line and an honest error bar. Every result we publish gets a defensible confidence interval once this lands.
Independent split-sample comparison
We want to run our pipeline against an ELAP-accredited FTIR/Raman lab on the same source water, and publish the chart — even if it makes us look bad. We have not lined up a partner lab yet.
Cross-kit reproducibility study
Five users running the same spiked standard through five different kits. If counts diverge by more than 2x, the kit isn't ready and we'll say so.
Open-source the counting code
Our YOLO-based particle counting model will be published on GitHub. Anyone can download it, audit it, run it on their own images, and tell us where it's wrong.
Want to verify any of this independently? Every public test result and the full underlying dataset is on thewatermap.com — free, open, no paywall, no signup.
The Paper We Cite
In 2022, Leonard et al. published a peer-reviewed paper in the Journal of Hazardous Materials Letters describing Nile Red fluorescence imaging for microplastic detection. Their reported method reliably detected and quantified microplastics as small as 10 µm (one-tenth the width of a human hair) across all common polymer types. That is the method we adapted for this kit.
To be explicit: the authors and their institution have not endorsed, reviewed, or validated this kit. We cite their paper because that's where the protocol comes from.
Leonard, J., Koydemir, H.C., Koutnik, V.S., Tseng, D., Ozcan, A., & Mohanty, S.K. (2022). “Smartphone-enabled rapid quantification of microplastics.” Journal of Hazardous Materials Letters, 3, 100052. DOI: 10.1016/j.hazl.2022.100052
Why This Matters Now
Microplastics have been found in:
- Arterial plaqueof heart patients — New England Journal of Medicine, March 2024
- Human blood, liver, kidneys, and placenta— multiple studies, 2022–2025
- Breast milk and infant meconium— meaning babies are exposed before birth
- Cerebral blood vessels— a 2025 Science Advances study linked bloodstream microplastics to thrombosis
California SB 1422 requires major utilities to test treated tap water starting Fall 2026.
New Jersey, Virginia, and Illinois have passed similar laws. The science is moving faster than the regulation. We think you shouldn't have to wait for the government to tell you what's in your water.
Results are provided for informational purposes and should not be interpreted as a regulatory or health determination. Data reflects individual household samples and may not represent municipal water system conditions.