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How this review was put together: from APEC’s product page and owner’s manual and the Water Quality Association’s public certification listing (links in “Sources” at the end). We have not tested this system ourselves. How we review. Last checked 28 October 2026.
The short version
The ROES-PH75 is a conventional under-sink reverse osmosis (RO) system with a storage tank: three pre-filters, a 75-gallon-per-day membrane, a carbon polishing filter, and a sixth calcite stage that adds a little calcium back and raises the pH of the water. It runs on household water pressure alone (no pump, no electricity), it uses standard-size 10-inch housings, and the whole system is WQA Gold Seal certified to NSF/ANSI 58.
The detail that matters most: the certified performance claim on WQA’s listing is TDS (total dissolved solids) reduction only. APEC’s long list of contaminants (lead, fluoride, PFAS, arsenic and so on) is the maker’s own claim, not part of the certification. RO membranes do generally reduce those substances, but if you are buying for one specific contaminant, that is a real difference (more on this below).
See the APEC ROES-PH75 on Amazon (paid link)
Who it suits, and who should look elsewhere
A good fit if you
- Want RO water at one kitchen tap and have a normal sink cabinet with room for a 4-gallon tank.
- Have household water pressure of roughly 50 psi or more. APEC’s manual shows the tank only gets to about half full at 40 psi, so pressure really matters with this model.
- Find plain RO water flat or slightly sour and prefer a remineralised taste.
- Like the idea of generic-size housings, so you are not locked into one brand’s proprietary cartridges.
Probably not the right pick if you
- Have low pressure (under about 40 psi), for example on some wells or upper floors. APEC tells low-pressure users to switch to a booster-pumped model.
- Need a certified claim for a specific contaminant such as lead, arsenic or fluoride. See the alternatives section below.
- Rent, or can’t drill a faucet hole or a drain line. A countertop RO unit avoids plumbing.
- Want filtered water from every tap. That’s a whole-house job, not an RO job (see is whole-house filtration worth it?).
Key specifications
From APEC’s product page and the ROES-PH75 owner’s manual, plus WQA’s certified figure.
| Spec | ROES-PH75 | What it means in practice |
|---|---|---|
| Type | Under-sink RO with pressurised storage tank, no pump | Works on house pressure; nothing to plug in. |
| Stages | 6: sediment, carbon block, carbon block, RO membrane, coconut-shell carbon post-filter, calcite pH filter | Carbon protects the membrane from chlorine; the last stage adjusts taste and pH. |
| Membrane rating | 75 gallons per day (at 60 psi, 77°F) | This is a lab-condition membrane rating, not what you’ll get at the tap. |
| Certified daily production | 27.9 gallons per day (WQA listing) | Measured under the NSF/ANSI 58 test conditions. Still plenty for drinking and cooking for most households. |
| Tank | 4 gallon total volume; holds about 3.2 gallons when full | Real stored water depends on your pressure (see the next table). |
| Feed pressure | 40–85 psi | Below 50 psi expect slower refills and a partly full tank. |
| Feed water temperature | 40–100°F, cold line only | Cold winter water slows production. |
| Max feed TDS | 2,000 ppm | Handles harder or saltier water than many RO units. |
| Feed pH range | 2.0–11.0 | |
| System size | 15.5 × 5.25 × 17.5 in (tank about 11 × 11 × 15 in) | Measure your cabinet, including the tank. |
| Warranty | 1-year limited product warranty (owner’s manual) | Filters and membranes are wear items and are not covered. |
How full the tank gets at different water pressures
This is the spec most listings leave out. APEC’s manual gives these figures for non-pumped ROES systems with the 4-gallon tank:
| Your incoming pressure | Approximate water in tank |
|---|---|
| 70 psi or more | about 3.1 gallons (nearly full) |
| 60 psi | about 2.8 gallons |
| 50 psi | about 2.5 gallons |
| 40 psi | about 1.9 gallons (around half) |
The tank also pushes water out more weakly as it empties, which is why APEC says you need at least 50 psi coming in if the RO line also feeds a fridge or ice maker. A cheap pressure gauge on an outdoor tap tells you where you stand before you buy.
Certification: what was verified
Status: Certified. The Water Quality Association’s Gold Seal directory lists the APEC ROES-PH75 under NSF/ANSI 58 (reverse osmosis drinking water systems), with a daily production rate of 27.9 gpd and a reduction claim of TDS. The listed replacement elements are FI-ES-SED10 (sediment), FL-ES-CAB10 (carbon block), MEM-ES-75 (membrane), FL-ES-TCR-QC (post-carbon) and FI-PHPLUS-QC (pH filter). WQA listing for APEC Water Systems (checked 28 Oct 2026).
What that does and doesn’t tell you:
- It does confirm that the complete system, not just a part, was tested for TDS reduction, materials safety and structural integrity, and that WQA audits the factory.
- It does not confirm APEC’s claims for lead, fluoride, arsenic, PFAS, bacteria or viruses on this model. Those appear on APEC’s product page, not on the certification listing.
- APEC’s own RO-90 family is listed by WQA with a much longer set of certified claims (arsenic V, barium, cadmium, copper, fluoride, chromium, lead, radium, selenium, turbidity). If a certified lead or fluoride claim is your main requirement, that family is the APEC to look at.
- We found no NSF International listing for this model. That is normal: WQA is an ANSI-accredited certifier testing to the same NSF/ANSI standards, so a WQA listing counts the same.
- Like every RO system, APEC’s manual says not to use it on water that is microbiologically unsafe or of unknown quality without disinfection. It is not a substitute for treating a contaminated well.
What we like and what to weigh up
Strengths
- The whole system is certified, not just the membrane or the housings. Plenty of RO units sold online only certify components.
- Standard 10-inch cartridges. Easier to source, and you are not stuck with proprietary twist-in filters.
- Copes with tough feed water: up to 2,000 ppm TDS and a wide pH range.
- No electricity, so nothing to fail electrically and nothing to plug in under the sink.
- A detailed owner’s manual, with tank-fill and pressure tables, TDS-check guidance and troubleshooting. Useful if you plan to install it yourself.
Drawbacks
- The certification is narrow (TDS only). The marketing contaminant list is much broader than the certified one.
- Sensitive to pressure. At 40 psi the tank only gets about half full, and APEC points low-pressure homes to a pumped model.
- It takes up cabinet space: a five-canister frame plus a separate tank.
- Waste water. Like any non-pumped tank RO system, it sends a large share of the incoming water to the drain. APEC’s materials don’t state a ratio for this model, so don’t expect tankless-level efficiency.
- A short base warranty in the manual (one year). Check APEC’s current terms when you buy.
- The pH filter is not a mineral supplement. It adds a small amount of calcium mainly for taste and pH. You will still get most of your minerals from food.
Maintenance and running costs
APEC’s schedule, from the ROES-PH75 manual:
| Stage | Part | Replace |
|---|---|---|
| 1–3 pre-filters | FILTER-SET-ES (sediment + 2 carbon blocks) | Every 6–12 months (sooner on well water with sediment) |
| 4 membrane | MEM-ES-75 | City water: every 2–4 years. Well water: about every 2 years |
| 5 post-carbon | FI-ES-TCR-QC | Every 2–4 years, ideally with the membrane |
| 6 pH / mineral | FI-PHPLUS-QC | Every 6–12 months |
| Housing O-rings | — | Yearly, or with each pre-filter change |
What drives the cost: the yearly pre-filter set and pH cartridge are the regular spend. The membrane and post-filter are the occasional bigger item every few years. Skipping pre-filter changes is the classic false economy, because worn-out carbon lets chlorine through and shortens the membrane’s life. Prices change often, so check the current cost of a pre-filter set and a membrane before you buy, and compare that over three years with the alternatives below.
A simple check that pays off: a handheld TDS meter. APEC says to test once or twice a year and replace the membrane when the RO water’s TDS rises to about 15–20% of your tap water’s.
Alternatives worth comparing
- Want certified lead and fluoride claims at a similar size? The iSpring RCC7AK-BLK is listed by NSF under NSF/ANSI 58 for lead, fluoride, barium, cadmium, copper, chromium, selenium, asbestos and TDS. Note the wording: that broader list applies to the BLK and BN versions.
- Prefer a big-box brand with retail support? See the Whirlpool WHER25.
- Short on cabinet space or want less waste? Tankless units such as the Frizzlife 600 GPD tankless RO skip the tank but need electricity.
- Renting or can’t drill? A countertop unit such as the Waterdrop CoreRO needs no plumbing.
- Under-sink RO from a premium brand: AquaTru Under Sink.
Common questions
Does the ROES-PH75 remove PFAS?
APEC lists PFAS, PFOA and PFOS among the things it removes, and RO is one of the point-of-use technologies the EPA found can greatly reduce PFAS. But PFAS is not a certified claim for this model on WQA’s listing. For more on what to look for, see is there a water filter that removes forever chemicals?
Will it remove the sodium from softened water?
RO is the usual way to take most of the sodium back out of softened water at the drinking tap. See how to remove sodium from softened water.
Can I connect it to my fridge?
Yes, there’s an ice-maker kit option. APEC’s guidance is that you need at least 50 psi of incoming pressure for steady delivery to an ice maker, and no more than three outlets in total.
Is the water “alkaline water”?
The calcite stage raises the pH and adds a little calcium for taste. It isn’t designed to produce high-pH “alkaline water” like an ionizer, and APEC doesn’t publish an output pH.
Check current availability of the APEC ROES-PH75 on Amazon (paid link)