PureLiving · Under-Sink RO Systems
RKIN Flash Undersink Reverse Osmosis System
Lower-concern product; standard RO filters use non-fluorinated polymers, but brand makes no PFAS disclosure.
Reverse osmosis systems typically use cellulose acetate or polyamide membranes and activated carbon, materials not inherently linked to PFAS. PureLiving does not publicly disclose PFAS testing or avoidance claims.
Shop PureLiving on Amazon →Material
RO membrane (cellulose triacetate or polyamide), carbon block, housing (polypropylene/ABS plastic)
Brand disclosure
Brand is silent on PFAS
Lab data
No public lab test
Why this grade
No PFAS disclosure
No public statement about PFAS in this product.
Safe base material
Made from a material with no inherent PFAS use (ceramic, mineral, or natural fiber).
The full breakdown
What it's made of and why it matters
The RKIN Flash uses a cellulose triacetate or polyamide RO membrane (industry standard, non-fluorinated), activated carbon block pre-filter, and polypropylene/ABS plastic housing. These materials are chemically stable during normal operation and do not leach into treated water under cold-water conditions. The membrane's role is passive filtration, not heat exposure, so thermal degradation is not a concern in undersink operation.
The brand's record and disclosure
PureLiving has not issued public PFAS avoidance statements or third-party certifications (NSF, WQA) that are recorded for this specific model. The brand does not market PFAS-free construction explicitly. No documented recalls or contamination incidents are on record for this product line. Lack of transparency on material sourcing is typical for budget RO brands but falls short of premium competitor disclosure standards.
How it compares in its category
Under-sink RO systems generally carry lower contamination risk than countertop models because they operate at low temperature and low pressure, reducing leaching likelihood. The RKIN Flash is positioned in the mid-budget segment; comparable systems (Waterdrop, iSpring, Culligan) often provide NSF certification or explicit PFAS policies, which this product does not highlight. Material choice (PP/ABS housing) is industry-standard and not a differentiator.
If you buy it
Replace the pre-filter cartridge every 6 months and the RO membrane every 2-3 years, or sooner if flow rate drops noticeably; delayed replacement allows bacterial biofilm growth in the storage tank. Ensure the system is installed with a shut-off valve and check valve to prevent backflow and stagnation. Do not expose the housing to direct sunlight or heat sources above 110°F (43°C). Flush the membrane for 5 minutes after installation and monthly if the system sits unused for more than a week.
Beyond PFAS: other things we checked
Established hazard classes for this product type, assessed from public information. These never change the PFAS grade; a Likely flag caps the Verdict at “Buy with care.”
Bacterial growth in storage tank
RO undersink systems store treated water in a pressurized tank; if not maintained or if filters are expired, bacteria can colonize the tank walls and tubing. PureLiving does not specify tank material disinfection protocol or recommend UV post-treatment, which is offered by higher-end competitors.
Polypropylene and ABS housing leachables
PP and ABS are FDA-approved for food contact and do not leach BPA or phthalates under cold-water, low-pressure RO conditions. No recalls or test reports documenting leaching from this brand's housing are on record.
Carbon block filter durability and microbial breakthrough
Activated carbon pre-filters can support bacterial growth if saturated or expired; this system does not include iodine-treated or silver-impregnated carbon (found in premium models). Replacement schedule adherence is user-dependent and not automated.
Degradation of membrane or tubing seals over time
Polypropylene tubing can weaken after 3-5 years of exposure to water pressure and chlorine residues, increasing leak risk. PureLiving does not specify tubing material specifications or expected service life in consumer documentation.
Improper installation leading to cross-contamination
If check valves or shut-off mechanisms fail or are omitted, treated and raw water can mix. The product manual's clarity on installation safety steps and valve inspection is not independently verified.
What we don’t know
This grade is a model-based estimate from public materials, coatings, and brand disclosure at 72% confidence. It is not a lab result.
No independent PFAS lab test is on record for this exact product. A lab test could move the score in either direction.
The brand has not made a specific, verifiable PFAS-free statement, so part of this score reflects that missing disclosure rather than a confirmed material.
Formulations and coatings change between production runs. Always check the current label before buying.
Safer alternatives in Under-Sink RO Systems
Aqua Guard
AQUASURE Premier Series 75 GPD Under Sink Reverse Osmosis Water Filtration System
RO membrane, carbon filters, stainless steel housing
Lower-concern RO system; standard filtration materials carry minimal PFAS risk, but brand is silent on the topic.
✓Bare metal or glass, no coating at all
Aqua Guard
AquaTru Under Sink Under Sink
Multi-stage filter cartridges (activated carbon, ion exchange resins)
Lower PFAS concern for standard under-sink filter use, but verify current cartridge specs before purchase.
✓Brand claims PFAS-free (unverified)
Home Master
TM Undersink Reverse Osmosis Water Filter System
Reverse osmosis membrane, carbon, sediment filters, stainless steel housing
Lower-concern RO filter system; no known PFAS materials identified, but brand makes no explicit PFAS commitment.
✓Bare metal or glass, no coating at all
More under-sink ro systems grades
How we score: every product runs through the same public 0–100 rubric based on materials, coatings, brand disclosure, lab findings, and recalls. See the full methodology → Spotted a mistake? Report an error.