SLF Water Filtration Comparison · 2026
VIVA21 6-Stage Alkaline RO
Recommended
Waterdrop G5P500
A strong value pick for households wanting a compact 500 GPD tankless RO system without paying for alkaline remineralization or premium smart-faucet features.
Waterdrop G5P500
Choose the G5P500 when you want more output than the G2P400 while keeping price and ongoing filter costs relatively low.
RO Performance & Ownership
Compare RO output, filtration stages, remineralization, contaminant evidence, certifications and ownership cost.
Which Is Right for You?
VIVA21 6-Stage Alkaline RO
Best for: Households wanting a traditional under-sink RO system with remineralization and a dedicated storage tank.
Consider if: Budget Under $300, Want Remineralization
Waterdrop G5P500
Best for: Value-conscious households wanting compact tankless reverse osmosis with 500 GPD capacity.
Consider if: Budget Under $300
Our Recommendation
VIVA21 6-Stage Alkaline RO
A compelling value-oriented alternative to higher-priced tankless RO systems for households that don't mind giving up cabinet space for a conventional storage tank.
Waterdrop G5P500
The Waterdrop G5P500 is a compelling value-focused tankless RO choice for households that prioritize filtration capacity and compact size over remineralization and smart faucet features.
The Short Answer
Choose the VIVA21 6-Stage if you want an affordable traditional under-sink RO system with alkaline remineralization and stronger certification positioning than many budget RO systems.
Choose the G5P500 when you want more output than the G2P400 while keeping price and ongoing filter costs relatively low.
Water Filter Comparison FAQs
Answers are generated from the current SLF product records for these two systems.
Which is better, VIVA21 6-Stage Alkaline RO or Waterdrop G5P500?
Waterdrop G5P500 is the overall pick for this specific matchup. Choose the G5P500 when you want more output than the G2P400 while keeping price and ongoing filter costs relatively low.
Which system has the higher daily filtration capacity?
Waterdrop G5P500 has the higher rated output: 500 GPD versus 50 GPD.
Which system offers remineralization?
VIVA21 6-Stage Alkaline RO: Yes. Waterdrop G5P500: No.
Which system has the lower MSRP?
Waterdrop G5P500 has the lower MSRP in the current SLF records at $249.99, compared with $339.99 for the other system.
Do both systems require a plumbing connection?
VIVA21 6-Stage Alkaline RO: Yes. Waterdrop G5P500: Yes.
Which system is more renter friendly?
VIVA21 6-Stage Alkaline RO: No. Waterdrop G5P500: No. Check lease and plumbing-modification rules before installing an under-sink system.
What certifications are listed for these systems?
VIVA21 6-Stage Alkaline RO: Manufacturer states VIVA21 6-Stage Alkaline RO (V21RS6S01PH) is WQA Gold Seal certified to NSF/ANSI 58 for RO system performance and NSF/ANSI 372 for lead-free materials. WQA Gold Seal is third-party product certification. SLF has not independently confirmed the exact model in WQA's public certified-product directory; retain manufacturer-source qualification pending direct directory verification. Waterdrop G5P500: Current Waterdrop G5P500 materials list IAPMO R&T certification to NSF/ANSI 372. Do not apply the G5P500A's NSF/ANSI 58 certification to the standard G5P500.
How do estimated annual filter costs compare?
VIVA21 6-Stage Alkaline RO: $60.00. Waterdrop G5P500: $104.98. Actual replacement timing and prices can vary.