The QuietlyGuide collection
Compare three tankless systems by certified claims, installation, drain-water use and replacement filters.
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Worth knowing More stated drain water per gallon than G3P800
Exact-model certification checked; manufacturer performance figures.
Check price at Waterdrop Read the detailsWorth knowing UV equipment included; no disinfection certification verified here
Exact-model certification checked; manufacturer performance figures.
Check price at Waterdrop Read the detailsWorth knowing NSF listing covers TDS reduction only
Exact-model certification checked; manufacturer performance figures.
Check price at iSpring Read the detailsThe details, together
GPD means gallons per day under rated conditions, not a guaranteed faucet flow. Pure:drain ratios are maker claims: 3:1 means three parts filtered water to one part drain water. Flushing, feed water and use patterns affect actual consumption. TDS is total dissolved solids; a low display reading does not verify every contaminant.
Comparing all 3 products. “Not listed” means the guide does not provide that specification.
Scroll across to compare products
| What matters to you | WaterdropG3P600 | WaterdropG3P800 | iSpringRO500-BN |
|---|---|---|---|
| Who it suits | The 600 GPD option | Higher output and a 3:1 ratio | A narrower cabinet unit |
| A useful strength | Same verified TDS/fluoride claims as G3P800 | Higher maker-rated output than G3P600 | Narrower cabinet unit than the Waterdrop pair |
| A trade-off to consider | More stated drain water per gallon than G3P800 | UV equipment included; no disinfection certification verified here | NSF listing covers TDS reduction only |
| Specifications | |||
| Maker-rated output | 600 GPD | 800 GPD | 500 GPD |
| Maker pure:drain ratio | 2:1 | 3:1 | Up to 2:1 |
| Verified reduction examples | TDS and fluoride; IAPMO listing | TDS and fluoride; IAPMO listing | TDS only in NSF listing |
| Certification scope | NSF/ANSI 58; named claims only | NSF/ANSI 58; named claims only | NSF/ANSI 58; named claims only |
| Drinking-water faucet | Included; smart display | Included; smart display | Included; brushed nickel |
| Electricity / drain | Both required | Both required | Both required |
| Cabinet unit (L × W × H) | Approx. 18.12 × 5.67 × 17.72 in | Approx. 18.12 × 5.67 × 17.72 in | 17.5 × 5.12 × 16.25 in |
| RO replacement | WD-G3P600-RO | WD-G3P800-RO (retail: G3P800-N2RO) | MRO500 |
| RO replacement timing | 24 months or 2,200 gallons | 24 months or 2,200 gallons | Up to 24–36 months |
| Evidence and availability | |||
| Evidence | 3 linked sources; limitations noted below | 3 linked sources; limitations noted below | 2 linked sources; limitations noted below |
| Customer opinion | None yet | None yet | None yet |
| Can you still buy it | Listed by maker, checked 4 October 2026 | Listed by maker, checked 4 October 2026 | Still sold, checked 4 October 2026 |
Specifications come from the sources listed under each product. Check the retailer for the exact model, package and current details.
Checked 4 October 2026 against Waterdrop US product page. Select the standard G3P600 system; bundle options can change the price and included hardware.
About the evidence: Exact system and replacement elements checked in the certifier’s directory. No hands-on testing or head-to-head filtration measurements. Certification covers named claims, not every contaminant advertised.
Consider this if the higher output of the G3P800 is unnecessary. Compare the current system price and membrane cost before choosing.
IAPMO lists WD-G3P600 with WD-G3P600-RO under NSF/ANSI 58, including TDS and fluoride reduction. The maker’s performance sheet also names these claims. Output and drain ratios below are manufacturer figures, not our measurements.
Sources: IAPMO — certificate WC-13976 · Performance data sheet (PDF) · Manufacturer — current system
| Maker-rated output | 600 GPD |
|---|---|
| Maker pure:drain ratio | 2:1 |
| Verified reduction examples | TDS and fluoride; IAPMO listing |
| Certification scope | NSF/ANSI 58; named claims only |
| Drinking-water faucet | Included; smart display |
| Electricity / drain | Both required |
| Cabinet unit (L × W × H) | Approx. 18.12 × 5.67 × 17.72 in |
| RO replacement | WD-G3P600-RO |
| RO replacement timing | 24 months or 2,200 gallons |
Source: https://www.waterdropfilter.com/products/waterdrop-reverse-osmosis-water-filtration-system
The maker lists CF at up to six months/550 gallons, CB at 12 months/1,100 gallons and RO at 24 months/2,200 gallons; replace at the earlier limit. The manual/certificate names are WD-G3-CF, WD-G3-CB and WD-G3P600-RO. Retail listings use N1CF/N3CB names; buy the G3P600-specific membrane. Match the system model before ordering. Reset reminders and flush replacements as the manual directs.
Sources: Installation and care manual (PDF) · Compatible membrane · Manufacturer filter schedule
Parts research checked 4 October 2026. Stock and package contents can change.
We have not added customer-review summaries or recorded price history for this product. The summary above is based on the linked sources. Visit the retailer for current prices and customer reviews.
Checked 4 October 2026 against Waterdrop US product page. Select the standard G3P800 system; bundle options can change the price and included hardware.
About the evidence: Exact system and replacement elements checked in the certifier’s directory. No hands-on testing or head-to-head filtration measurements. Certification covers named claims, not every contaminant advertised.
Consider this if the higher output and lower stated drain-water use justify the extra cost. Both Waterdrop units need similar cabinet space.
IAPMO lists WD-G3P800 with WD-G3P800-RO under NSF/ANSI 58, including TDS and fluoride reduction. The maker’s performance sheet also names these claims. Output and drain ratios below are manufacturer figures, not our measurements.
Sources: IAPMO — certificate WC-13976 · Performance data sheet (PDF) · Manufacturer — current system
| Maker-rated output | 800 GPD |
|---|---|
| Maker pure:drain ratio | 3:1 |
| Verified reduction examples | TDS and fluoride; IAPMO listing |
| Certification scope | NSF/ANSI 58; named claims only |
| Drinking-water faucet | Included; smart display |
| Electricity / drain | Both required |
| Cabinet unit (L × W × H) | Approx. 18.12 × 5.67 × 17.72 in |
| RO replacement | WD-G3P800-RO (retail: G3P800-N2RO) |
| RO replacement timing | 24 months or 2,200 gallons |
Source: https://www.waterdropfilter.com/products/tankless-reverse-osmosis-system-wd-g3p800-w-fc-1
The maker lists CF at up to six months/550 gallons, CB at 12 months/1,100 gallons and RO at 24 months/2,200 gallons; replace at the earlier limit. The manual/certificate names are WD-G3-CF, WD-G3-CB and WD-G3P800-RO. Retail listings use N1CF/N3CB names and G3P800-N2RO for the compatible membrane. Match the system model before ordering. Reset reminders and flush replacements as the manual directs.
Sources: Installation and care manual (PDF) · Compatible membrane · Manufacturer filter schedule
Parts research checked 4 October 2026. Stock and package contents can change.
We have not added customer-review summaries or recorded price history for this product. The summary above is based on the linked sources. Visit the retailer for current prices and customer reviews.
Checked 4 October 2026 against iSpring US product page. Standard RO500-BN with FCB500 postfilter; not RO500AK.
About the evidence: Exact system and replacement elements checked in the certifier’s directory. No hands-on testing or head-to-head filtration measurements. Certification covers named claims, not every contaminant advertised.
Consider this for TDS reduction where cabinet width matters. Its certification listing does not establish the same contaminant claims as the Waterdrop models.
NSF lists RO500-BN with FCF500, MRO500 and FCB500 for TDS reduction under NSF/ANSI 58. The listing does not certify its broader marketing claims for specific contaminants.
Sources: NSF — exact system and filter listing · Manufacturer — current system
| Maker-rated output | 500 GPD |
|---|---|
| Maker pure:drain ratio | Up to 2:1 |
| Verified reduction examples | TDS only in NSF listing |
| Certification scope | NSF/ANSI 58; named claims only |
| Drinking-water faucet | Included; brushed nickel |
| Electricity / drain | Both required |
| Cabinet unit (L × W × H) | 17.5 × 5.12 × 16.25 in |
| RO replacement | MRO500 |
| RO replacement timing | Up to 24–36 months |
Source: https://www.ispringfilter.com/ispring-ro500-bn-tankless-ro-reverse-osmosis-water-filtration-system-500-gpd-fast-flow-brushed-nickel-faucet-21-pure-to-drain-ratio-white-nsf-certified
Maker guidance allows up to six months for FCF500, 12 months for FCB500 and 24–36 months for MRO500. The F3-RO500 annual pack contains two FCF500 filters and one FCB500; the membrane is separate. Follow the manual’s flushing and reminder-reset steps. Water conditions can shorten these intervals.
Sources: Installation and care manual (PDF) · Annual pre/postfilter pack · Replacement membrane
Parts research checked 4 October 2026. Stock and package contents can change.
We have not added customer-review summaries or recorded price history for this product. The summary above is based on the linked sources. Visit the retailer for current prices and customer reviews.
Prices change constantly; check the shop before buying. Summaries are written in our own words from the sources linked on each product. We do not test products in a lab.
