Choosing water filtration starts with a practical question: do you want a permanent drinking-water setup, a countertop gravity system, or a compact filter for short-term tap use? The four options here cover very different formats, from a 600 GPD under-sink reverse osmosis system to a small Sawyer tap filter, so the right pick depends less on one universal "best" and more on where you plan to use it, how much capacity you want, and how much you want to spend.
Quick take
- Best fit for high-output under-sink reverse osmosis: Waterdrop D6 Reverse Osmosis Water Filter, 600 GPD Under Sink Reverse Osmosis, with a tankless design, smart faucet, and listed 600 GPD capacity.
- Best fit for countertop gravity filtration: BLEMISHED Berkey Water Filter System w/ WQA Certified Boroux Black Filters, with a polished stainless steel body, Big 2.25g capacity, and two black filters.
- Best fit for a lower-priced under-sink RO setup: 5 Stage Undersink Reverse Osmosis Water Filter System 75 GPD Membrane Filter, which uses a five-stage reverse osmosis layout.
- Best fit for compact tap-connected emergency use: Sawyer Tap Filter Water Filtration System Fast Emergency Water SP134, the lowest listed price in this group and built around a UF membrane format.
Listed price comparison
The listed prices span from USD 34.49 to USD 229.99, with the lowest-priced Sawyer option sitting 85% below the highest-priced Berkey system.
| Product | Listed price | Price bar |
|---|---|---|
| Sawyer Tap Filter Water Filtration System Fast Emergency Water SP134 | USD 34.49 | |
| 5 Stage Undersink Reverse Osmosis Water Filter System 75 GPD Membrane Filter | USD 116.09 | |
| Waterdrop D6 Reverse Osmosis Water Filter, 600 GPD Under Sink Reverse Osmosis | USD 179.00 | |
| BLEMISHED Berkey Water Filter System w/ WQA Certified Boroux Black Filters | USD 229.99 |
Decision matrix
| Shopper priority | Strongest match | Why it fits |
|---|---|---|
| Highest listed daily output | Waterdrop D6 Reverse Osmosis Water Filter | The title and attributes point to 600 GPD under-sink reverse osmosis, and the description adds a tankless format with a smart faucet. |
| Countertop gravity format | BLEMISHED Berkey Water Filter System | It is described as a stainless gravity countertop system with Big 2.25g capacity and two Boroux black filters. |
| Multi-stage RO at a midrange position | 5 Stage Undersink Reverse Osmosis Water Filter System | The five-stage layout includes sediment, GAC, CTO, RO membrane, and post-carbon stages in the description. |
| Portable tap-focused use | Sawyer Tap Filter Water Filtration System SP134 | It is compact, tap-connected, and includes adapters such as a hose, cleaning adapter, nozzle adapter, and spare o-ring. |
| New condition only | Simpure 5 Stage system or Sawyer SP134 | Both are marked new, while the Waterdrop is certified refurbished and the Berkey is open box. |
Concise product notes
Waterdrop D6 Reverse Osmosis Water Filter, 600 GPD Under Sink Reverse Osmosis
The Waterdrop D6 is the capacity-forward under-sink choice, pairing reverse osmosis with carbon block filtration and a listed 600 GPD rating. Its description points to a tankless design, built-in booster pump, smart faucet with LED display, real-time TDS monitoring, and filter life indicator, which makes it the most feature-dense RO option in this comparison. It also includes a low drain ratio claim in the product text. The main tradeoff is that it is marked Certified - Refurbished, and the description states that an electrical outlet is required, so it is less simple than a passive countertop or compact tap filter.
BLEMISHED Berkey Water Filter System w/ WQA Certified Boroux Black Filters
The Berkey system is the countertop gravity option for shoppers who want a stainless steel format rather than an under-sink reverse osmosis unit. It includes two Boroux black filters, has a Big 2.25g capacity, and lists compatibility with Berkey and Boroux models including BU2, TU2, CU2, and IU2. The title includes "WQA Certified Boroux Black Filters," and the description references NSF/ANSI 42, 401, and 372 standards for the Boroux Foundation filters. The limitation is right in the title and condition: it is described as BLEMISHED and marked Open box, and it is the highest-priced item in the group.
5 Stage Undersink Reverse Osmosis Water Filter System 75 GPD Membrane Filter
The Simpure five-stage system is the more traditional under-sink reverse osmosis pick here, with a 75 gal capacity attribute and a listed filtration precision of 0.0001 micron. Its staged layout is straightforward: PP sediment, GAC, CTO, RO membrane, and post-carbon T33 filter. That makes it a clear match for shoppers who want a multi-stage RO setup without stepping up to the Waterdrop D6's larger-output, smart-faucet approach. The limitation is output: 75 GPD is far below the Waterdrop's 600 GPD figure, and the description also presents multiple filter elements with replacement intervals, so ongoing cartridge attention is part of the format.
Sawyer Tap Filter Water Filtration System Fast Emergency Water SP134
The Sawyer SP134 is the compact outlier: instead of being a full under-sink or countertop system, it is a tap filter aimed at fast emergency water use. It uses UF membrane filtration technology, is black, marked new, and includes connection pieces such as a hose, cleaning adapter, nozzle adapter for garden taps, hose adapter, double-sided adapter, and spare o-ring. The description also lists a 0.1 micron hollow fibre membrane and tap connection guidance. Its limitation is scope: it is built around faucet or garden tap attachment, including a stated 17-20 mm hole diameter, so it is not the same type of household fixture as the under-sink RO systems or the Berkey countertop unit.
How to choose among them
Start with placement. If you want an under-sink reverse osmosis system, the comparison narrows to the Waterdrop D6 and the Simpure five-stage system. The Waterdrop is the higher-output, more electronics-oriented choice, with tankless construction, a smart faucet, and a 600 GPD rating. The Simpure is the simpler five-stage RO choice, with universal compatibility language and a 75 GPD membrane filter setup.
If you prefer a countertop system, the Berkey is the only gravity-fed countertop format in the group. Its polished stainless steel color and Big 2.25g capacity make it distinct from the under-sink products. It also has the broadest named compatibility language, spanning Berkey and Boroux systems and several model codes.
If your priority is compactness and emergency-style tap use, the Sawyer is the clearest match. It is also the lowest listed price, which makes it very different from the larger home-system options. The tradeoff is that it is a tap-connected filtration system rather than a full installed RO or gravity countertop setup.
Condition may also matter. The Simpure and Sawyer are marked new. The Waterdrop is certified refurbished. The Berkey is open box and also described as blemished. Those condition differences may be just as important as capacity or filtration method if you are choosing between similar formats.
Final recommendation
For most shoppers comparing permanent drinking-water setups, choose by format first. Pick the Waterdrop D6 Reverse Osmosis Water Filter if you want the strongest listed output in this set and are comfortable with a certified-refurbished, powered under-sink RO system at USD 179.00. Pick the 5 Stage Undersink Reverse Osmosis Water Filter System if you want a new under-sink RO setup with a five-stage layout at USD 116.09.
Choose the BLEMISHED Berkey Water Filter System w/ WQA Certified Boroux Black Filters if a stainless gravity countertop system with Big 2.25g capacity is the priority and the open-box, blemished condition works for you at USD 229.99. Choose the Sawyer Tap Filter Water Filtration System Fast Emergency Water SP134 if you want the compact tap-connected option and the lowest listed price, USD 34.49.