See the microplastics in your tap water.
$50 at-home kit. Plastic particles stain pink under UV — the same peer-reviewed method used in research labs. Two tests per kit, so you can compare tap to filtered.
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New results from the lab, every week. No spam.
What it actually looks like.
Two real samples from our lab. Every glowing pink dot is a plastic particle caught on the filter.
Bottled water (1 yr old plastic)
80+ particles
Clean baseline sample
4–6 particlesReal customer results
Some filters work. Some don't.
Three real test results from paying customers across Los Angeles. Every one of these is a real photo, a real particle count, and a real filter.
RO is pulling its weight.
An under-sink RO system in Fox Hills came back at 2 and 5 particles. Another in Duarte came back at 9 and 0. Both filters are doing their job.
See Fox Hills on the map
Whole-house is holding up.
A whole-house system in Santa Monica came back at 8 and 9 particles across two samples — about where a working filter should land.
See Ocean Park on the map
A fridge filter in Pacific Palisades.
Samples came back at 17 and 10 particles — roughly the same as unfiltered tap in this dataset. The family thought their kids were drinking filtered water. The filter wasn't doing much.
See Pacific Palisades on the map
Every result, every image, every particle count is already public on thewatermap.com. Click any card to see the neighborhood data.
From cup to pink dots in under an hour.
10 minutes of hands-on work. The rest is the dye doing its job.
Order your kit
Everything ships to your door. Two complete tests included.
Run the test
Stain, filter, shine the blue light. 10 minutes of hands-on work.
See your results
Microplastics glow pink. Upload a photo — we count the particles.
The science behind the test. Read the methodology
Who's behind this
I built a fluorescence microscopy lab in my garage to test my own tap water.
Hi, I'm Andrew. I started this after reading that the average person eats a credit card's worth of plastic every week — and realizing nobody could actually show me what was in my own water.
So I built a lab in my garage. Nile Red dye, blue light, a filter that traps particles down to a micron. It works. And it's simple enough that I packaged it into a kit anyone can run at home — on whatever water they want to test.
If you can fill a glass with water, you can do this. No science degree required.
Follow the research
Get updates on what I'm testing next — new homes, new filters, new cities.
Every glowing dot is a microplastic particle.
Every home is different.
Some are clean. Some aren't. What will you find in yours?
Weekly dispatch
See what we're finding each week.
New neighborhoods, particle counts, photos — the ones worth seeing. No filler, no selling. Unsub anytime.
No spam. Unsubscribe anytime.
Everything you need. $50.
Common questions
What does the test actually detect?
Plastic particles trapped on a filter, stained with Nile Red dye, glowing pink under a blue LED. Upload a photo of your filter and we give you a particle count, a severity rating, and a comparison to other homes.
Can I test my filter?
That's the #1 reason people order. Run a sample from your tap, then a sample from the filtered side, and compare. It works on Reverse Osmosis, whole-house, under-sink, fridge filters, pitchers — anything you can fill a cup with.
What if I don't have a filter yet?
Even better — test your tap first. You'll know whether a filter is worth buying, and if you do install one later, you'll have a real before-and-after on your own water.
Is this hard to do?
If you can fill a glass with water, you can do this. Everything's included, two complete tests per kit, about 10 minutes of hands-on work.
More questions? See the full FAQ or read about how it works.