The orange glass has smudges or specks on it.

Leave it in place and wipe it with a microfiber cloth, the same way you'd clean glasses. Anything on the glass is only in your view, not on the filter, so it doesn't change the count.

How do I clean the amber bottle for another test?

Run it through the dishwasher. Don't drink from it.

Can I cover the bottle while the dye works?

Yes. Foil, a lid, or a plate on top all work, and covering it keeps dust out.

The syringe is too hard to push.

Don't force it. Pull the plunger back, unscrew the filter holder, reseat the filter so it sits flat, screw it back on, and push again gently and steadily. The full push should take 20 to 30 seconds.

The filter came out unevenly wet. Is that normal?

Yes. Dab it with a paper towel until it's slightly damp and it will flatten out. Bone-dry, it curls.

What's the difference between bright dots and dim dots?

Bright dots are particles that took up the stain, and they're counted as likely microplastics. Dim dots are usually dust, mineral, or something slightly out of focus. Count the bright ones.

Is a glowing line or streak a microplastic?

That's a fiber. A glowing fiber is often plastic, such as polyester or nylon from clothing, though some natural fibers can also pick up the stain. Count it as one particle.

Can I read the filter without the microscope?

You can see the big bright ones by eye under the blue light, but you'll miss most of the small ones. Use the microscope for the count.

Could I have contaminated the sample by handling it?

A stray fiber or two from the air or your clothes can land on the filter, and that won't change the overall picture. Keep the filter covered when you're not looking at it. Touching it after the dye has worked doesn't add stain.

Nothing glows. Is my water clean?

Check two things before you trust it. The microscope's own light has to be all the way off, because white light washes out the glow. Then check the flashlight batteries: below about half charge the beam still looks bright but no longer makes the dye glow, so a real sample reads as clean.

The background looks orange or red instead of dark.

Normal. The tint varies from deep red to orange depending on the light and the filter. Particles still show up as bright dots on top of it.

How long do I have before the filter stops glowing?

About 24 hours. No need to rush to the microscope.

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.

Use the microscope

Turn the microscope's light all the way off

The microscope has its own built-in light. Turn it all the way down until it is completely off. The blue flashlight is the only light the filter should get. Under the microscope's white light the stained particles stop glowing, and a filter with plastic on it reads as empty.

Instructions

Test your water for microplastics

Have the original kit?

One sample at a time. Most of the 30 minutes is waiting after you add the vial.

Two parts. Tap one to open it.

Filling the amber glass jar with water at the faucet

1.Collect 100 mL of water

1 min

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.