Air purifier buyers increasingly add a water line — same retail shelf, same consumer promise (health), same replacement-consumables economics. But RO water purifiers are a different sourcing discipline: pressure systems, food-contact materials and membrane performance replace fans and CADR. Here is how the category actually works when you buy it OEM.
Two platform families, two different products
| Countertop RO (instant hot) | Under-sink RO (high flow) | |
|---|---|---|
| Installation | None — plug in, fill the tank | Plumbed under the kitchen sink |
| Typical user | Renters, offices, small kitchens, tea & baby-formula use | Families cooking and drinking daily |
| Key specs | Tank 4–6 L · heating 15–21 L/h ≥90 °C · ~2200 W | Flow 2–6.5 L/min · tankless or small pressure tank |
| Differentiators | Instant-hot accuracy, ice-maker or coffee-maker combos, nanobubble options | Flow rate, wastewater ratio, filter-change interval |
| HOKO platforms | SJ-100R series · SC-RO2018-03 · SJ-137-A01 (ice maker) · WH-01 (nanobubble) · WH-02 (capsule coffee) | SJ75R-A01 (200G) · SJ-600NW-A02 (6.5 L/min) |
Countertop is the faster category to launch: no installation means no plumber network, no install-related returns, and a product that demos well on video. Under-sink wins on daily throughput and is the repeat-purchase engine in markets where families cook with purified water. Many importers run countertop first, then add under-sink once the brand has traction.
The documentation that actually matters
- Food-contact material reports. Every wetted part — tanks, tubing, faucet — needs migration testing by an accredited lab. Ask for the reports per material (ABS, PP, silicone), not a single generic certificate.
- Membrane performance. The RO membrane is the product. Ask for the membrane element test report (ours runs 26 items on the SJ75R membrane) and the rated total net water flow — that number defines real filter life.
- Water efficiency. Pure-to-drain ratio matters for marketing claims and, in some markets, for compliance. Get the water efficiency test report from a CMA/CNAS lab.
- Electrical safety and EMC. Instant-hot units are 2200 W heating appliances — CE/ETL-equivalent safety files apply exactly as they do for air purifiers, per model.
- Hygiene suite. Total plate count and permanganate index testing on the finished unit (see the SJ-137 series hygiene report FW250903-14 in our test report center).
Questions that expose an assembler
- Who makes the membrane element and the filter cartridges? Vertical integration matters as much here as in air filters — our filter division produces cartridges on the same campus, which is what makes long-term replacement programs priceable.
- What is the per-unit outgoing test? Correct answer: pressure testing on every unit, not sampling. Water appliances fail wet.
- What is the rated total net water flow, and how was it measured? This is the CADR of the water world — see our guide to reading performance test reports for the same verification discipline.
- What does the replacement filter program look like at year 3? Cartridge price, change interval, packaging with your brand. The machine is the razor.
MOQ, samples and lead time
Same commercial frame as our air line: MOQ 500 units for light customization (color, logo, packaging, panel), 40–50 working days for mass production, stock samples in 1–7 days with the sample fee refunded against the formal order. Water platforms add one step: we recommend a wet test on your local water chemistry before finalizing the filter stack for your market — TDS and hardness vary enough to change cartridge specification. Start with your target market and quantity — the reply includes the per-model food-contact and efficiency documentation list.