That’s exactly what happens. With the AquaTru Carafe, the reject water does go back into the same unfiltered tank, and that’s actually by design. The system is constantly recirculating that water until the clean side fills, which is what makes this unit so much more efficient compared to traditional RO systems that just send the reject water down the drain. The key thing is to always dump out the dirty tank before refilling with fresh tap water, otherwise the reject water will just keep getting concentrated and run back through the membrane, risking scaling.

I’ve tested a few of their products:
https://waterfilterguru.com/waterdrop-countertop-reverse-osmosis-water-filter-system-review/
https://waterfilterguru.com/waterdrop-x-series-review/
https://waterfilterguru.com/waterdrop-chubby-review/
https://waterfilterguru.com/waterdrop-g3-review/
https://waterfilterguru.com/waterdrop-king-tank-review/

You’re right, turbidity (NTU) only measures cloudiness, not particle size. To know what micron level of filtration you need, you’d have to go further. Labs can measure particle size distribution with laser diffraction or microscopy, but in practice most people use staged filtration (like 20, 5, then 1 micron) and see which filter clogs first. That indirectly tells you the dominant particle size. For everyday use, turbidity plus knowledge of your water source is usually enough to guide filtration choices.

Carbon filters. Keep in mind reduction rates are impacted by contact time, and sometimes water flowing through those small faucet filters is too fast for high removal rates.

Let me clarify. The line you’re seeing in that table is showing Brita’s official NSF/ANSI 401 certification for microplastics reduction. That means the Elite filter has been independently certified to meet the NSF standard, which requires reducing particles in the 0.5–1 micron range by at least 85%. Brita’s published data shows a 99.6% reduction.

What I don’t have, and what I try to point out in my videos and reviews, is any firsthand lab test data on microplastics from my own side-by-side testing. My independent testing has focused more on things like heavy metals, chlorine, and VOCs. I do plan to include microplastics as well in the future when testing costs become feasible.

Also, just to clear up one other point — the PFOA and PFOS you see listed above are PFAS chemicals, not microplastics. They’re a completely different category of contaminants, even though they’re often talked about in the same breath because they’re both “emerging contaminants.”

Both Clearsource and Amazon are distributors of On the Go products. Clearsource is not the manufacturer.

I’ve heard similar stories from folks comparing the old ZeroWater filters to the new ones since Culligan acquired the company