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Waterdrop D6

Ranked #23 of 50 in Best Reverse Osmosis Systems (2026). Here is every spec we scored, where it came from, and how it compares.

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#23

Waterdrop D6

Best for: 6-stage 600 GPD tankless RO with a 1.5:1 pure-to-drain ratio

1.5/10

What we like

    Watch out for

    • Highest drain water per product gallon in this comparison (0.667 gal/gal)
    • Warranty not published by Waterdrop

    Score breakdown

    Daily production 24%
    NSF/ANSI 58 named 20%
    Broader named certification 16%
    Drain water per product gallon 16%
    Filtration stages 12%
    Warranty * 12%

    * Not published by the manufacturer; scored at the lowest published value in this category, so an unpublished figure never outranks a published one.

    Daily production600 GPD
    NSF/ANSI 58 namedNo
    Broader named certificationNo
    Drain water per product gallon0.667 gal/gal
    Filtration stages6
    WarrantyNot listed
    Daily production (maker)600 gallons per day
    Filtration stages (maker)6 stages
    NSF/ANSI 58 (maker)Not listed
    Broader named certificationNot listed as a broader named certification on the page we used
    Drain ratio (maker)1.5:1 pure-to-drain (official page)
    Drain water per product gallon0.667 gal/gal (computed)
    Warranty (maker)Not listed
    Design (maker)Tankless, smart faucet
    Package weight (maker)22.2 pounds
    Dimensions (maker)15.98 x 5.98 x 11.97 inches
    PriceCheck price
    Check price at Amazon
    Specs source:

    How it compares

    Open the full comparison table

    Waterdrop X16
    7.5/10
    #1 · 11-stage 1,600 GPD tankless RO, NSF/ANSI 42 and 58 named, 3:1 pure-to-drain
    Waterdrop X12
    6.9/10
    #2 · 11-stage 1,200 GPD tankless RO, NSF/ANSI 42 and 58 named, 3:1 pure-to-drain
    Waterdrop X12-PRO
    6.9/10
    #3 · 11-stage 1,200 GPD dual-flow tankless RO, NSF/ANSI 42 and 58 named
    Waterdrop X14
    6.9/10
    #4 · 11-stage 1,400 GPD alkaline tankless RO, NSF/ANSI 42 and 58 named
    Waterdrop X8
    6.1/10
    #5 · 9-stage 800 GPD tankless RO, NSF/ANSI 42 and 58 named, 2:1 pure-to-drain
    Waterdrop X8-PRO
    6.0/10
    #6 · 9-stage 800 GPD dual-flow tankless RO, NSF/ANSI 42 and 58 named
    Waterdrop G3P600
    5.3/10
    #7 · 8-stage 600 GPD tankless RO, NSF/ANSI 42 and 58 named, 2:1 pure-to-drain
    Waterdrop G3P800
    4.1/10
    #8 · 9-stage 800 GPD tankless RO with UV, NSF/ANSI 58 named, 3:1 pure-to-drain
    iSpring RCC7AK
    4.1/10
    #9 · NSF/ANSI 58 certified 6-stage 75 GPD alkaline under-sink RO
    APEC ROTL-A1000ALK
    3.8/10
    #10 · 5-stage 1000 GPD alkaline tankless RO, NSF/ANSI 58 and 372 named in the official title
    APEC ROTL-A1000
    3.6/10
    #11 · 4-stage 1000 GPD tankless RO, NSF/ANSI 58 and 372 named in the official title
    iSpring RO500-BN
    2.8/10
    #12 · NSF/ANSI 58 certified 500 GPD tankless RO with a 2:1 pure-to-drain ratio
    iSpring RCC7AK-UV
    2.6/10
    #13 · NSF/ANSI 58 certified 7-stage 75 GPD alkaline and UV under-sink RO
    iSpring RCC7U
    2.5/10
    #14 · NSF/ANSI 58 certified 6-stage 75 GPD UV under-sink RO
    iSpring RCC7
    2.3/10
    #15 · NSF/ANSI 58 certified 5-stage 75 GPD under-sink RO
    APEC RO-PH90
    2.1/10
    #16 · 6-stage 90 GPD alkaline under-sink RO with a named WQA contaminant list
    APEC RO-90
    2.0/10
    #17 · 5-stage 90 GPD under-sink RO with a named WQA contaminant list
    Waterdrop T4-A
    1.8/10
    #18 · 450 GPD alkaline dual-flow under-sink RO with a 2:1 pure-to-drain ratio
    iSpring RO1200
    1.8/10
    #19 · 1,200 GPD dual-flow tankless RO with a 3:1 pure-to-drain ratio
    Waterdrop G5P700A
    1.8/10
    #20 · 8-stage 700 GPD alkaline tankless RO
    Waterdrop G5P700
    1.7/10
    #21 · 7-stage 700 GPD tankless RO with a 2:1 pure-to-drain ratio
    Waterdrop T3-M
    1.6/10
    #22 · 9-stage 450 GPD remineralizing under-sink RO with a 2:1 pure-to-drain ratio
    Waterdrop G5P500
    1.3/10
    #24 · 7-stage 500 GPD tankless RO
    iSpring RO800G
    1.2/10
    #25 · 800 GPD tankless RO with an up-to 2.5:1 pure-to-drain ratio
    iSpring RO600-BN
    0.9/10
    #26 · 600 GPD tankless RO with a 2.5:1 pure-to-drain ratio
    APEC ROTL-600
    0.9/10
    #27 · 3-stage 600 GPD tankless under-sink RO
    APEC ROTL-AIO
    0.9/10
    #28 · 600 GPD all-in-one tankless under-sink RO
    iSpring RCC2AK-UV
    0.8/10
    #29 · 7-stage 200 GPD alkaline and UV under-sink RO
    iSpring RO5004F-AK
    0.8/10
    #30 · 500 GPD alkaline tankless RO with UV and a 2:1 pure-to-drain ratio
    iSpring RCC1UP-AK
    0.7/10
    #31 · 7-stage 100 GPD alkaline under-sink RO with a booster pump and UV
    iSpring RCC2AK
    0.7/10
    #32 · 6-stage 200 GPD alkaline under-sink RO
    APEC ROES-PHUV75
    0.6/10
    #33 · 7-stage 75 GPD alkaline and UV under-sink RO
    iSpring PH100
    0.5/10
    #34 · 6-stage 100 GPD alkaline under-sink RO
    iSpring RCC2
    0.5/10
    #35 · 5-stage 200 GPD under-sink RO
    APEC ROES-PH75
    0.5/10
    #36 · 6-stage 75 GPD alkaline under-sink RO
    APEC ROES-UV75-SS
    0.5/10
    #37 · 6-stage 75 GPD UV under-sink RO with a stainless housing
    iSpring RCC1UP
    0.5/10
    #38 · 6-stage 100 GPD under-sink RO with a booster pump and UV
    iSpring RCD100
    0.4/10
    #39 · 5-stage 100 GPD countertop RO with UV and a 2.5:1 pure-to-drain ratio
    iSpring RO100
    0.4/10
    #40 · 5-stage 100 GPD under-sink RO
    APEC RO-Hi
    0.4/10
    #41 · 5-stage 90 GPD fast-flow under-sink RO
    APEC RO-PERM
    0.4/10
    #42 · 5-stage 90 GPD under-sink RO with a permeate pump for low-pressure homes
    APEC ROES-100
    0.4/10
    #43 · 5-stage 100 GPD under-sink RO
    iSpring RCC100P
    0.4/10
    #44 · 5-stage 100 GPD under-sink RO with a booster pump
    APEC ROES-50
    0.3/10
    #45 · 5-stage 50 GPD under-sink RO with a 4-gallon tank
    iSpring RCC7P
    0.3/10
    #46 · 5-stage 75 GPD under-sink RO with a booster pump
    APEC RO-CTOP-C
    0.2/10
    #47 · Portable 4-stage 90 GPD countertop RO with a carry case
    APEC RO-CTOP-PH
    0.2/10
    #48 · Portable 4-stage 90 GPD alkaline countertop RO
    APEC RO-QUICK90
    0.2/10
    #49 · Compact 4-stage 90 GPD under-sink RO
    iSpring RO10001F
    0.0/10
    #50 · Tankless under-sink RO with a 3:1 pure-to-drain ratio and 0.69 GPM listed flow