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FilterScored

Water · Best-of

Best Reverse Osmosis System

Bottom line

The best reverse osmosis system pairs genuine NSF/ANSI 58 certification with a low cost per gallon and an efficient wastewater ratio.

If you want the widest contaminant coverage in one system, reverse osmosis (RO) is it - it filters at the membrane level, catching dissolved contaminants that carbon filters miss. What you trade for that reach is two things: it sends some water down the drain, and the running cost per gallon runs higher. We score RO systems on what they're certified to reduce, what they cost to run, and how efficiently they use water, so you can see all three at once.

How we score: We rank reverse-osmosis systems by overall score, which weights certified contaminant reduction, cost per gallon, and how much water goes to waste per gallon produced.

  1. 17.5
    AquaTru Classic Countertop RO

    The AquaTru Classic Countertop RO is a ro water filter. It is third-party certified (IAPMO) to reduce lead, PFOA, PFOS, fluoride, arsenic, chromium-6, nitrate, chlorine taste and odor, chloramine, VOCs, microplastics. Running cost works out to about $0.287 per gallon.

    • Certified to reduce: lead, PFOA, PFOS, fluoride, arsenic, chromium-6, nitrate, chlorine taste and odor, chloramine, VOCs, microplastics
    • Cartridge life: 600 gallons
    • Cost per gallon: $0.287
  2. 26.6
    Waterdrop G3P800 Tankless RO

    The Waterdrop G3P800 Tankless RO is a ro water filter. It is third-party certified (IAPMO) to reduce chlorine taste and odor, total dissolved solids (TDS), lead, fluoride, cadmium, chromium-6, selenium, arsenic, nitrate, mercury, copper, barium, PFOA, PFOS. Running cost works out to about $0.123 per gallon.

    • Certified to reduce: chlorine taste and odor, total dissolved solids (TDS), lead, fluoride, cadmium, chromium-6, selenium, arsenic, nitrate, mercury, copper, barium, PFOA, PFOS
    • Cartridge life: 2,200 gallons
    • Cost per gallon: $0.123
  3. 36.1
    iSpring RCC7 5-Stage RO

    The iSpring RCC7 5-Stage RO is a ro water filter. It is third-party certified (NSF) to reduce total dissolved solids (TDS). It is also marketed for lead, fluoride, arsenic, cadmium, chromium, copper, selenium, chlorine taste and odor, PFAS, for which we found no accredited third-party certification (so we award no certification credit; this is not a finding that it fails to reduce them). Running cost works out to about $0.024 per gallon.

    • Certified to reduce: total dissolved solids (TDS)
    • Cartridge life: 547,500 gallons
    • Cost per gallon: $0.024
  4. 44.9
    Express Water RO5DX 5-Stage RO

    The Express Water RO5DX 5-Stage RO is a ro water filter. It carries no accredited NSF, WQA, or IAPMO certification - its contaminant claims are "tested to" lab results, not certifications. It is also marketed for lead, arsenic, fluoride, chromium, mercury, uranium, radium, chlorine taste and odor, chloramine, total dissolved solids (TDS), for which we found no accredited third-party certification (so we award no certification credit; this is not a finding that it fails to reduce them). Running cost works out to about $0.021 per gallon.

    • Certified to reduce: nothing certified (claims are 'tested to' only)
    • Cartridge life: 4,380 gallons
    • Cost per gallon: $0.021
  5. 54.3
    Home Master TMAFC-ERP Artesian RO

    The Home Master TMAFC-ERP Artesian RO is a ro water filter. It carries no accredited NSF, WQA, or IAPMO certification - its contaminant claims are "tested to" lab results, not certifications. It is also marketed for chlorine taste and odor, chloramine, lead, fluoride, total dissolved solids (TDS), arsenic, pharmaceuticals, microplastics, for which we found no accredited third-party certification (so we award no certification credit; this is not a finding that it fails to reduce them). Running cost works out to about $0.038 per gallon.

    • Certified to reduce: nothing certified (claims are 'tested to' only)
    • Cartridge life: 27,375 gallons
    • Cost per gallon: $0.038
  6. 64.0
    APEC ROES-50 Essence RO

    The APEC ROES-50 Essence RO is a ro water filter. It is third-party certified (WQA) to reduce total dissolved solids (TDS). It is also marketed for chlorine taste and odor, lead, arsenic, fluoride, VOCs, for which we found no accredited third-party certification (so we award no certification credit; this is not a finding that it fails to reduce them). Running cost works out to about $0.145 per gallon.

    • Certified to reduce: total dissolved solids (TDS)
    • Cartridge life: 550 gallons
    • Cost per gallon: $0.145

FAQ

How much water does RO waste?
It varies a lot by system, so it's worth checking before you buy. Older designs send 3 or more gallons down the drain for every gallon they make; efficient tankless models can get close to 1-to-1. We put the wastewater ratio on each scorecard so you can compare.

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