Express Water RO5DX 5-Stage Reverse Osmosis System (50 GPD) review
Under-sink reverse osmosis. Plumber recommended if you are not comfortable with a drain saddle and a tank. Not a whole-house solution. Listed to NSF/ANSI 58.
What it removes
| Contaminant | Evidence | Stated reduction | Scope |
|---|---|---|---|
| Lead | Manufacturer-reported | 99.37% | |
| Arsenic | Manufacturer-reported | 98.15% | |
| Fluoride | Manufacturer-reported | 99.83% | |
| Nitrate (as N) | Manufacturer-reported | 99.26% | |
| Uranium | Manufacturer-reported | 99.01% | |
| Chromium (total) | Manufacturer-reported | 99.63% | |
| Chlorine (residual) | Manufacturer-reported | 98.62% | |
| Total Dissolved Solids | Manufacturer-reported | not stated |
Certified is an NSF, WQA, or IAPMO listing for that claim.
One drinking-water tap. Not a whole-house solution.
Certifications
- NSF/ANSI 58: TDS Reduction (listing checked 2026-09-14)
Entry-price tank-style 5-stage RO (sediment, GAC, carbon block, 50 GPD membrane, post-carbon), 4 gal tank (3.2 gal water), 0.8 GPM faucet flow stated by manufacturer, non-electric, leak-stop valve. Manufacturer price $189.99. Amazon ASIN B00J2DGTD8 appears in Amazon search results with the correct title but every proxy fetch on 2026-09-14 returned a bot-check page, so title and price could not be verified (amazon_verified false; price is manufacturer's). Amazon title claims 'NSF Certified 372 & 58' but the expresswater.com product page names no certifier and the model is not in NSF's listing database, so no certification row is recorded. Percentages below come from Express Water's test-results page (QFT Laboratory, NSF/ANSI 58-2020 method) for its RO systems generally, not a model-specific data sheet. Annual filter cost not published on the pages fetched.