Hydrologic · Under-Sink RO Systems
Hydro Logic Stealth RO300 Reverse Osmosis Filter
Lower concern, RO filters use standard polymer membranes without typical PFAS application, but brand discloses nothing.
Reverse-osmosis filters rely on pressure-driven polymer membranes and carbon cartridges, which are not typical PFAS-application contexts. Hydrologic provides no public statements about PFAS in this product.
Shop Hydrologic on Amazon →Material
RO membrane (cellulose acetate), polyamide layers, carbon pre-filters, housing (plastic/metal)
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 Stealth RO300 uses a cellulose acetate RO membrane as its primary filtration layer, backed by polyamide (nylon) support membranes and granular activated carbon pre-filters. Cellulose acetate is a well-established, non-toxic polymer for water filtration; polyamide is chemically inert under cold-water conditions. The housing combines plastic (typically polypropylene or ABS) and metal fittings. None of these materials are known to leach harmful substances into drinking water under normal reverse osmosis operating conditions (cold water, low pressure).
The brand's record and disclosure
Hydro Logic is an established US-based water filtration manufacturer with no major product recalls or safety controversies on public record. The brand provides standard product documentation and NSF listings but does not publish detailed material composition or third-party testing summaries on its website. No certifications for heavy metals, bacterial safety, or chemical leaching appear to be independently marketed, though the product meets baseline NSF/ANSI standards for RO systems.
How it compares in its category
The RO300 is a mid-range under-sink system; it sits between budget models (higher risk of housing degradation) and premium systems (often with added remineralization or UV stages). Standard RO technology is uniform across reputable brands; the main variables are filter replacement frequency, housing durability, and post-filtration stages. Hydro Logic's design is conventional and not differentiated by material choice or claimed safety advances.
If you buy it
Replace carbon pre-filters and RO membranes on the manufacturer's recommended schedule (typically 6-12 months for pre-filters, 2-3 years for membrane) to prevent bacterial biofilm and reduced filtration efficiency. Inspect plastic fittings and tubing annually for cracks or cloudiness, as UV exposure or temperature swings can degrade polyethylene tubing over time. Store replacement filters in a cool, dry place; do not expose the RO membrane to freezing temperatures. Flush the system after extended non-use to prevent stagnant water in the tank.
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 and tubing
RO systems produce low-pressure, low-chlorine water that can support microbial growth if not used regularly or if storage tanks are not cleaned. The Stealth RO300 uses a pressurized tank; bacteria risk is lower than in open reservoirs but increases if filters are not replaced on schedule or system sits unused for weeks.
Leaching from plastic housing and fittings
Polypropylene and ABS are stable under cold, low-pressure water conditions typical of RO systems. No established recalls or test data indicate leaching of BPA, phthalates, or other endocrine disruptors from Hydro Logic housings. Risk remains minimal if system is not exposed to heat or UV.
Carbon filter dust and loose media
Granular activated carbon pre-filters can shed fine particles if not properly contained or if cartridges are damaged during installation. This does not contaminate the drinking water (it is trapped by the RO membrane) but may reduce pre-filter performance and increase membrane fouling over time.
Tubing and connector degradation
Polyethylene or polyurethane tubing used to connect the RO unit to the tap can crack, cloud, or become brittle under temperature fluctuations or if left exposed to sunlight. Degraded tubing does not introduce chemical contaminants but can harbor bacteria and compromise system integrity.
Membrane pore integrity loss over time
RO membranes naturally degrade with use and exposure to chlorine, sediment, or biofouling; the Stealth RO300 does not appear to include a chlorine-removal pre-filter stage in base specifications. Membrane tears or compression after 2-3 years may not produce a visible change in water clarity but can reduce rejection of dissolved contaminants, including some pharmaceuticals and industrial chemicals.
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.