THE WATER TESTStep 1 of 12
Step 11 min

Collect 100 mL of water

Filling the amber glass jar with water at the faucet

Fill the jar almost to the top with the water you're testing. It holds about 100 mL (3.5 oz). Leave room for the 1 mL vial you add next. Results are reported per 100 mL, so use the full jar.

Step 215–20 min wait

Add the vial and wait

Adding the reagent vial to the amber glass jar with a dropper

Add the vial, swirl gently, and wait 15–20 minutes. Longer is better; the dye needs time to bind.

Cover the jar while you wait. Dust from the air lands in an open jar and gets counted.

Step 31 min

Put the filter in the holder

Open the holder, drop the filter in, twist it shut

Unscrew the holder, set the round filter membrane inside, and screw it back together.

Step 41 min

Attach the holder to the syringe

Twist the holder onto the syringe tip until snug

Twist the assembled filter holder onto the syringe tip until it's snug.

Step 51 min

Fill the syringe

Pouring prepared water into the top of the syringe

Pour the prepared water into the top of the syringe.

How many times to fill it

If you have a 60 mL syringe, fill and push it roughly twice. If you have a 100 mL syringe, fill and push it once. Either way, keep going until the jar is empty so the full 100 mL sample passes through the same filter.

Unscrew the filter holder before you pull the plunger back for the second fill. Pulling against the filter can damage it.

Step 6Right away

Push the water through

Pushing a water sample through the syringe filter

Push the water through right away; don't let it sit.

Step 71 min

Retrieve the filter

Unscrewing the filter holder to retrieve the filter membrane

Unscrew the holder and take out the filter. Keep the side that faced the water pointing up. That's the side you read.

Step 81 min

Put the filter in the imaging box

Setting the round filter into the square window of the imaging box

Place the filter inside the imaging box, collection side up.

Step 91 min

Put the glass on the lid

Setting the orange glass square over the window on top of the imaging box

Set the glass on the box lid — it rests in the square indentation.

Step 101 min

Add the flashlight

Sliding the flashlight into the rectangular hole on the top-left of the box

Slide the flashlight into the rectangular hole on the top-left of the box.

Step 111 min

Take the photo

A phone resting on top of the imaging box with its camera app open, showing the glowing filter

Open your camera app, rest the phone flat on the box with the lens over the glass, tap the glowing filter to focus, then shoot.

Turn on Night Sight. No exceptions.

Without it, the camera won't pick up the glow and your count will be useless. Takes 5 seconds.

Step 121 min

Upload your photo

Upload the photo you just took. Our particle counter reads it on the spot — your microplastic count appears right here, and a verified report follows by email within 24 hours.

Swipe or tap the arrows to continue
Have the new digital-microscope kit? See those steps

Two things to check

These details can make particles harder to see. If the screen looks unusual, check both before reading the result.

Keep the membrane very flat

If the 25 mm filter disc curls or buckles, the light can hit it unevenly and create darker areas. Handle it with the tweezers and try to keep it very flat while you read it.

Dab it with a paper towel until slightly damp. Damp makes the disc stick flat; bone-dry, it curls.

Check the flashlight batteries

The flashlight is fixed in place, so aiming isn't the problem — the batteries are. Below about 50–70% charge the blue light stops exciting the dye and nothing glows, even with plastic on the filter. You won't see it happen: a half-dead cell still throws a beam that looks bright. If the kit was finding particles and then stopped, put in fresh batteries before you trust a clean result.

How the imaging box works

The box blocks room light and lines up the filter, flashlight, and camera. Particles that took up the stain glow under the blue light — those are the ones we count as likely microplastics.

Then count it in the app

Once the box is set up, the app walks you through capturing and counting the particles.

Compare two sources

Have two tests? Run one on unfiltered tap water and one after your filter.

When you're done

Wash the jar thoroughly. Don't drink from it.

Want to test again?

Each refill covers one more run — keep the blue light, syringe, glass slide, and imaging box you already have. sold separately.

Get a refill

Stuck on a step? Use the chat in the bottom-right corner.

Don't have a kit yet? The microplastics test kit is available to order online. Tests are sold separately.