The Water Filter Lab
Clean Water, Clear Answers
The Water Filter Lab is an independent resource for homeowners researching water filtration. We compare certifications, published specifications and install reality to explain which systems actually solve common contamination problems — from PFAS-targeted carbon blocks and reverse osmosis (RO) systems to everyday pitchers and whole-house installations. We do not run a lab: every guide is grounded in NSF/ANSI certification listings and manufacturers' published specifications, so you can choose the right filter for your water, your budget, and your home.
A free lookup guide. Enter a ZIP code or choose city water or a private well, then open EPA's Consumer Confidence Report finder, the EWG Tap Water Database, or CDC's well-testing guidance. We do not show contaminant data for any ZIP code. From the words on your own report, the page points at a filter type and the guides that match it.
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Our fall 2026 reverse osmosis picks by home type: tankless under-sink, budget tank systems, and no-install countertop RO, with what each one does and does not do.
Under-sink picks for 2026, matched to each certification on the data sheet: Aquasana AQ-6200, Waterdrop G3P800, iSpring RCC7, and Waterdrop's T4-A.
No single well-water filter fits every well. Test for coliform, nitrate, iron and hardness, then match a whole-house system or an under-sink RO.
Which filters actually reduce fluoride (reverse osmosis, activated alumina, some specialty pitchers), which don't (standard carbon), and where the EPA fluoride review stands in fall 2026.
Waterdrop vs Aquasana, and Aquasana vs Waterdrop: G3P800 tankless RO versus the Claryum AQ-6200 carbon filter, on certification, minerals, and wastewater.
Best tankless RO in 2026: G3P600 at 600 GPD and 2:1, or G3P800 at 800 GPD, 3:1 and UV. APEC ROES-50 is the no-power tank. WQA lists it for TDS.
Countertop RO, under-sink RO, or a pitcher when you rent. What the C1SL, G3P800, and G3P600 actually require, without guessing at your lease.
How to read an RO drain ratio. Published numbers for the Waterdrop G3P800, G3P600, iSpring RCC7, and APEC ROES-50, and why a tank often uses more water.
EPA's public-water nitrate limit is 10 mg/L as nitrogen. Iron and carbon filters do not list nitrate. Here is which RO sheets we read that do.
Mini-fridge shelves are short. Brita's 10-cup listing shows 10.1 and 10.47 inch heights. Clearly Filtered publishes 10.87. Measure the gap first.
Aquasana's WH-1011 sheet lists 83% overall chloramine reduction. SpringWell guarantees below detection, and we found no NSF certificate for it.
Waterdrop's C1SL is a 75 GPD countertop RO with a 3:1 drain ratio. The US page lists no NSF certification. Here is what the manual does limit.