RKIN U1 & U1-W Review: Lab Analysis & Hands-On Testing

Full Analysis of the RKIN U1 and U1-W

Please note: RKIN U1 and RKIN U1-W are identical in terms of filtration hardware, performance, third-party contaminant reduction testing, and usability. The only difference is the U1-W’s app integration for monitoring water quality, usage, filter status, and remote system control.

Filtration: 3.87/5.00

The RKIN countertop RO system scored 3.87/5.00 for filtration. How? Most importantly, it achieved solid results in our lab testing and the filtered water tasted clean with no odor. The system has no NSF/ANSI-certified contaminants but does have third-party testing for the reduction of several impurities.

1. Lab Results: 4.37/5.00 (2025)

In our lab test comparing an unfiltered and a filtered tap water sample, the RKIN could remove 7 undesirable impurities and contaminants to below the minimum detection level (so essentially to 100%): chlorine, copper, barium, iron, manganese, nitrate, and fluoride.

The following substances remained in our water:

• Bromodichloromethane was reduced by a high 87%.
• Dibromochloromethane was reduced by 86%, which is high as well.
• Chloroform was also reduced by a high 88%.
• Boron was reduced by a very high 94%.
• Strontium increased by 92%, which is unlikely to be due to natural fluctuations and may indicate potential leaching. Fortunately, even at 0.211 ppm, it was still ~7x lower than the strictest health guideline of 1.5 ppm published by the EWG.

Finally, TDS decreased by 87%. While TDS should not be interpreted independently, as it does not override inadequate removal of individual contaminants, ≥85% reduction is good, just not as high as other RO systems we tested. That said, the U1 utilizes a remineralization post-filter, which adds beneficial minerals back into the water and increases its TDS. Consequently, the slightly lower amount of TDS removal that we observed is to be expected.

Remineralization Results

In our lab testing, we measured 0.356 ppm magnesium and 4.42 ppm calcium post-filtration, neither of which were within their respective WHO health guidelines (minimum 10 ppm, optimal 20-30 ppm for magnesium and minimum 20 ppm, optimal ~50 ppm for calcium). While these levels were higher than those observed in the non-remineralized RO systems we tested (average of 0.11123 ppm magnesium and 0.47253 ppm calcium), they still reflect limited mineral restoration.

Post-remineralization pH increased to 7.3 (compared to an average of 6.72 without remineralization), and alkalinity rose to 13 ppm – below the IDPH-recommended range of 30–400 ppm but still higher than the 2.2 ppm average of non-remineralized systems. However, elevated pH in particular should not be interpreted as an indicator of adequate mineral content, as direct mineral concentrations remained low.

Overall, the mineral cartridge improved buffering capacity and taste-related parameters but did not meaningfully restore essential minerals to health-recommended levels.

That said, our remineralization lab results represent a standardized, worst-case scenario designed to reflect the shortest possible contact time between purified RO water and remineralization media, ensuring consistency across all tested systems. Additional testing using TDS meters and extended contact times showed considerably higher TDS levels, suggesting increased mineral dissolution under those conditions. This minimal-contact approach may therefore underrepresent real-world remineralization performance.

In the RKIN, water is remineralized inline before dispensing. A small amount of purified water remains in and around the internal mineral cartridge after each use. If the unit sits idle, that water stays in contact with the media longer, which may allow additional mineral dissolution.

Users who dispense small amounts at a time and allow the system to rest between uses may therefore see somewhat higher mineral levels than observed under our minimal-contact lab conditions. In contrast, dispensing larger volumes at once results in shorter contact time and performance closer to our test results.

We did not measure the cartridge’s internal retention volume, so while real-world mineral levels may exceed our lab findings under certain usage patterns, the extent of that increase remains unknown.

Lab Results Chart

2. NSF/ANSI Certifications and Other Test Data

The RKIN does not have any NSF/ANSI certifications for contaminant reduction. However, it does have third-party testing for the reduction of 7 contaminants against NSF/ANSI standard 58.

Reported reduction rates include:

• Chromium 3 (99.62%)
• Chromium 6 (99.28%)
• Fluoride (95.25%)
• Lead (99.80%)
• PFOA (97.63%)
• PFOS (98.56%)
• TDS (92.86%)

Reduction rates are per RKIN’s third-party test reports.

3. Filtration Process

We have 3 filter cartridges, a hydrogen post-filter and a UV light post-filter, which comprise 6 filtration stages.

• Stages 1 + 2 are performed by the composite pre-filter (sediment pre-filter + activated carbon block). Stage 1 is the sediment pre-filter; this performs mechanical filtration, acting like a sieve to remove solid, undissolved particulates such as dirt or rust. Stage 2 is an activated carbon block which removes things like bad tastes and odors, chlorine/chloramine, disinfection byproducts and other organics, as well as certain metals. Removing chlorine and other contaminants protects the RO membrane from damage. In addition, the block structure provides fine mechanical filtration due to its smaller pore size compared to granular carbon.
• Stage 3 is the RO membrane, which uses reverse osmosis to effectively remove the vast majority of contaminants and minerals.
• Stage 4 is the remineralization post-filter, which restores minerals like calcium and magnesium, raises the pH, and boosts the water’s flavor.
• Stage 5 is the hydrogen post-filter, which generates hydrogen-enriched water. RKIN claims the dissolved molecular hydrogen may act as an antioxidant, potentially reducing harmful reactive oxygen species to lower oxidative stress. That said, according to our research, to date no large studies have confirmed the potential health benefits of hydrogen-enriched water. Note: Hydrogen is optional and can be turned off.
• Stage 6 is the UV post-filter, which exposes the filtered water to germicidal UV radiation prior to dispensing, inactivating microorganisms. This provides chemical-free disinfection; however, in our view, it should not be relied upon to make non-potable water safe to drink, but rather to help control microbial regrowth in stored water and prevent off-tastes from stagnation. In the U1, the UV light is applied to the cold water only.

4. Taste and Odor Test

In our test, the filtered water was odorless and had a perfectly clean taste.

Usability: 3.69/5.00 (U1-W: 3.83/5.00)

The RKIN U1 achieved a usability score of 3.69/5.00, based on its performance in the following categories:

1. Initial system assembly including filter priming (0.80/0.80)
2. Everyday use (2.39/3.70)
3. Filter replacements (0.50/0.50)

The RKIN U1-W achieved a usability score of 3.83/5.00, based on:

1. Initial system assembly including filter priming (0.80/0.80)
2. Everyday use (2.53/3.70)
3. Filter replacements (0.50/0.50)

1. Initial Setup: 0.80/0.80

Assembling the RKIN U1 is easy, even if it was a bit intimidating when we first unboxed it. The system is large and very heavy, with lots of buttons on the touch screen. However, our worries were unfounded thanks to the clear, illustrated user manual complemented by a quick-start sheet, which contains a QR code linking to the digital manual. Plus, there’s a helpful tutorial video on YouTube.

Here’s a quick breakdown of the setup procedure:

1. Place the system and drip tray on a stable surface within 3 feet of an electrical outlet.
2. Remove the feed water tank and completely empty it if needed. Fill the fresh tap water compartment with tap water up to the max fill line. Place tank back onto the base and close the lid.
3. Plug cord into power outlet. Press and hold the power key for 2 sec. The system will start automatically filtering water.
4. Place 1 gal or larger container under the dispenser to collect water that will dispense during the rinse cycle.
5. Once the “fresh water” notification is displayed, press and hold the “rinse” button for 3 seconds. Wait for the process to finish in about 6 min.
6. Repeat steps 2, 4 and 5 two more times for a total of 3 rinse cycles.
7. Now your system is ready to use.

For the U1-W, setup is exactly the same, only that you also connect to the app via Wi-Fi, which is easy. The quick-start sheet provides a QR code which link to the app download.

2. Day-to-Day Use: 2.39/3.70 (U1-W: 2.53/3.70)

2.1 Speed & Water Capacity: 0.60/0.98

The RKIN is generally suited for daily use though it lacks a carafe or external pure tank for instantly accessible water. Plus, its pump-driven dispensing speed for ambient, hot, and cold water is very slow.

You can fill a 40-oz bottle from a single feed tank in one continuous dispense – no need to refill the feed tank in between or wait for additional cycles of water processing. Plus, most standard 40-oz bottles should fit under the spout without tilting, as its height is 11.5″ from the base.

Unlike a 40-oz bottle, you can’t fit a standard 2-quart carafe under the spout, as it’s not high enough. However, assuming you found a container that would fit, you could still dispense 2 quarts in a single button push without refilling the feed tank.

More specifically and using a full feed tank (~1.58 gal), in our test the system could dispense 84 oz of ambient water continuously before stopping.

The RKIN also dispensed 63 oz of the hottest water in one continuous pour, which should be plenty for pretty much all beverages and instant food.

While the system allowed us to dispense 80 oz on the cold water setting all at once, the water was only cold for the first 16 oz or so. Since cooling took around 45 minutes, you realistically can only get ~2 cups of refreshingly cold water at one time.

The RKIN struggles somewhat with dispensing speed, particularly in our thirst round test. Here we evaluate whether a system can produce 2.55 and 3.15 ambient cups of water in less than 30 sec per cup without having to refill – in other words, fast enough to quickly quench the thirst of the standard-sized US and US family households. The RKIN didn’t quite pass muster: in our ambient water speed tests, it could dispense 1 cup in 38.5 sec or 4 cups in 2:21 min when the water was pre-processed, meaning the feed tank was filled and allowed to filter this water first. Upon refilling the tank, it took 3:29 min to dispense 4 cups of water.

Still, it’s fast enough to meet the maximum daily water needs of the average-sized US households, and it can handle thirst bursts – which we define as 8-10 cups in an hour.

We also investigated how much ambient filtered water could be produced from one full feed tank, regardless of how much time or how many button pushes it took to fully process and dispense this entire volume. For the RKIN, this maximum volume was 97 oz (~12.1 cups). Assuming 25.5 cups or 31.5 cups of daily water consumption for the average US and US-family households, respectively, and 12.1 cups filtered water per full feed tank, we estimate 3 daily refills – about average for the countertop ROs we tested.

As with ambient water, both cold and hot water dispensing speed are very slow. It took 43.5 sec to dispense 1 cup of cold pre-processed water – longer than average for the cold water countertop RO systems we tested.

Hot water required 46 sec to dispense 1 cup of pre-processed water, though this is pretty typical for the hot water countertop RO systems we tested. Hot water is particularly slow to dispense because it must be heated on-demand; flow must be slow enough to give it time to reach the desired temperature.

Fortunately, the RKIN provides volume presets and numerous customization options. This helps to offset the inconvenience of slower dispensing speeds, allowing you to step away from the system while it works on your pour.

2.2 Dispensing: 0.70/0.70

Dispensing ambient or on-demand hot/cold water is simple and splash-free. The RKIN’s responsive touch screen admittedly looks overwhelming at first, as there are numerous buttons and icons with which you must become familiar. However, once you get the lay of the land it is actually very simple and the customization options are plentiful.

This system can dispense cold (≤59 °F), ambient, or hot water up to 212 °F. You may also choose from one of several customizable water temperature options, namely Milk (baby formula setting; 109-127 °F), Coffee (167-185 °F), Tea (176-203 °F), and Hot (194-212 °F). Temperatures are customizable in 1 °F increments for the most nuanced control over your water.

Volume is also highly customizable. You can choose from multiple preset options, including Small Cup (5, 7, or 9 oz), Big Cup (10, 12, 14, or 16 oz) or up to 0.5 gal at once, fine-tuning it in 1-2 oz increments as needed.

You can stop dispensing early if necessary by pushing the dispense button again, but in our test it took a couple of seconds for the system to ramp down. We think most people would get used to this after a while, but it may result in a few overfilled glasses until you get the hang of the timing. Fortunately, the magnetic drip tray can help catch residual droplets.

There is no display reading for cold water temperature on this system. However, there is a child safety lock to keep your family safe from accidental hot water injuries.

2.3 Hot Water: 0.50/0.56

More on the hot water:

As mentioned above, the RKIN can dispense enough hot water for virtually all typical household use cases – which we define as at least 32 oz at a time. In fact, in our test it could dispense up to 63 oz of ~193.6 °F water at one time. In other words, it can produce sufficient hot water for beverages like tea, coffee or hot chocolate (8-16 oz), instant noodles/soup (14-20 oz), and cooking assist/pot jump-start (16–32 oz).

The actual temperature of the dispensed hot water was quite close to the preset values at the lower temperature settings. Based off the unit’s presets, we measured (RKIN preset vs. our thermometer):

• 118 °F vs. 117 °F
• 185 °F vs. 184.5 °F
• 194 °F vs. 191.5 °F
• 212 °F vs. 193.6 °F

At the higher preset levels, the RKIN struggled to fully heat the water; in fact, at the highest setting, the actual measured temp was lower than the preset value by more than 18 °F.

Assuming 190–195 °F is reliable for most beverages and instant foods, with ≥200 °F being the optimal, kettle-equivalent performance, the RKIN gets hot enough for most typical uses – even if it doesn’t reach the boiling temperatures (212 °F) that it advertises.

2.4 Cold Water: 0.32/0.56

More on the cold water:

Despite continuously dispensing 80 oz of water on the cold setting, only the first ~16 oz were actually chilled after allowing for sufficient cooling time. Consequently, the RKIN can dispense about 2 cups of genuinely cold water every 45 minutes, which is enough to fill one person’s glass. But assuming ≥20 oz enables bottle refills, ≥32 oz supports extended use, and ≥48 oz is needed for multiple people or to fill a carafe, this system is pretty limited in its cold-water capacity.

RKIN advertises a cold water temp of ≤59 °F – we found the system had no trouble achieving this when tested with our own thermometer, ranging from 44.4-51.4 °F for the first two cups.

In other words, the U1 produces acceptably chilly water – just not very much of it. Considering <41 °F is fridge-cold, with 41–45 °F reaching near-fridge temps and 46-50 °F still feeling refreshingly cold, the U1 achieved solid marks for its ability to produce bracingly cold water.

In addition, cooling is optional on the RKIN and can be activated or inactivated by pressing and holding the Cold button for 3 seconds.

2.5 Refilling & Size: 0.07/0.49

Refilling the U1 is a chore. The feed water tank is large and heavy – especially when full – and latches onto hooks located in the back of the unit. Plus, the max fill line goes right up to the divider inside the tank, so some water may spill over and get lost to the waste compartment if you’re not careful during reinstallation.

To make matters worse, wastewater leaks out of the bottom valves when tipping the tank over for emptying. And because the tank is so tall, for us that usually meant water leaking out onto the floor or counter.

That said, it does have a water shortage/change indicator to remind you when it’s time to empty the wastewater and refill.

Measuring 9.5″x17.2″x18.4″ (WxHxD), the RKIN U1 just fits under standard height (18”) kitchen cabinets, and at a whopping 32 lbs (measured for the U1-W), we’d classify it as very heavy. Its footprint is also above-average compared to the other tested systems, occupying a massive ~174.80 in² (~1.21 ft²) – definitely not space-saving. In fact, dimensions-wise, it is the largest countertop RO we tested by far. Plus, at nearly 10” wide it is not streamlined enough to fit in narrow spots.

2.6 Other: 0.21/0.42 (U1-W: 0.35/0.42)

While maneuverability is impeded by the U1’s hulking size, it has several other redeeming factors that affect its overall usability:

For one, the unit’s display shows TDS readouts or hydrogen content of the filtered water as follows:

• When the hydrogen function is on, hydrogen content in ppb is displayed.
• When the hydrogen function is off, filtered water TDS is displayed.

TDS monitoring of the filtered water enables you to keep an eye on the system’s filtration performance over time. We found the TDS readings to be fairly accurate – within 15 ppb of a separate meter.

We also like the dispense button that indicates the temperature of the water being poured: white for ambient water, red for hot, and blue for cold.

However, as mentioned this system lacks a carafe or external pure tank to store water for later – you have to dispense into a glass, bottle, or your own container.

The U1-W app allows for remote control of the system (turning it on/off, choosing water temp and dispensing amount, locking/unlocking hot water, activating/deactivating hydrogen function and manual flushing). It also monitors TDS of the filtered water and filter status.

3. Filter Replacements: 0.50/0.50

Filter replacements are easy as the filters are readily accessible after removing the housing lid and quickly twist in/out. A filter wrench is included if you need the extra leverage.

The filter change indicator lights on the display also alerts you when it is time to change each filter. Rated filter life for the composite pre-filter is 792 gal or 6-12 months, the RO membrane is 1-2 years, the remineralization post-filter is 792 gal or 6-12 months, and the hydrogen post-filter is 6-12 months.

Assuming 500 gallons of yearly water consumption for the average household, we predict the frequency of your filter changes will be dictated by filter age rather than water consumption. Therefore, expect to replace them every 6-24 months if following the manufacturer’s recommendations.

For the U1-W, the app displays remaining filter life reminding you to replace filters.

Costs: 2.79/5.00 (U1-W: 2.86/5.00 )

Based on value for money, the RKIN U1 achieved a cost score of 2.79 out of 5.00, while the RKIN U1-W achieved 2.86 out of 5.00, indicating both are priced above average for what they offer compared to competing systems (a score of 4.00 represents average value). Notably, their upfront prices are well above average and annual filter replacement costs are substantially above average compared to the other ambient/hot/cold water countertop RO systems we tested.

1. Upfront Price

As of November 4, 2025, the RKIN U1 is priced at $845.12, the U1-W at $875.12, which is well above the $587.71 average across all the tested countertop RO systems that produce ambient/hot/cold water.

2. Long-Term Expenses for Filter Replacements

Based on 500 gallons consumption and a 792-gal or 6 to 12-month rated filter life (composite pre-filter), 1-2 year filter life (RO membrane), 792-gal or 6 to 12-month filter life (remineralization post-filter), and 6 to 12-month filter life (hydrogen post-filter), we estimate $170-340 in annual filter replacement costs.

However, we feel the more frequent 6-month filter changes for the composite pre-filter, remineralization post-filter and hydrogen module may be appropriate given the limited third-party testing and lack of NSF/ANSI-certifications for contaminant reduction. Plus, a 6-month rated filter life is fairly standard for these components across most countertop RO systems, including those that come with more thorough testing. That said, a 2-year RO membrane life is customary across countertop ROs, so changing this filter once every 2 years should be sufficient.

Based on these intervals, we estimate $300 in annual filter replacement costs, which is substantially above the $149.47 average across all the tested countertop ROs.

3. Product Warranty

The system is covered by a 1-year warranty. It also comes with a 1-year satisfaction guarantee, though this has a 25% restocking fee after the 30-day return window.

4. Other Cost Factors

Other features which we feel boost the U1’s value include:

• Hydrogen infusion (can be turned off if desired).
• Hydrogen content in ppb is displayed when hydrogen feature is on.
• Window of the front tank allows you to see hydrogen bubbling.
• UV light to prevent stagnation of the (cold) filtered water.
• Accurate TDS measurements of the filtered water.
• Child safety lock to prevent hot water injuries.
• Feels very sturdy.
• Highly customizable water temps and volumes.
• U1-W only: App integration.

Additional

1. Pure-to-Drain Ratio Test

We measured a pure-to-drain ratio of ~1:1.08 which is low wastewater for RO systems in general but worse than the average ~1:0.61 across the countertop RO systems we tested.

2. Construction

The system appears extremely sturdy and well built. It’s also very large and heavy, but that contributes to its high-quality feel.

3. Design

The RKIN U1 has a pleasing, modern design. Its black color and solid build almost make it look like an espresso machine – not at all out of place on your kitchen counter.

4. Manual Flushing

Manual flushing is activated with the “Rinse” button on the unit or in the app. RKIN recommends performing a flush after filter changes, when the system hasn’t been used for 3 days or more, or when 2 weeks or more have passed since the last rinse cycle.

While flushing counters TDS creep and extends RO membrane life, it may also waste water.

5. Hydrogen Infusion Window

If hydrogen is turned on, the window in the front of the tank is illuminated with a blue light, allowing visualization of the hydrogen bubbles when this function is active. This looks especially striking against the black body of the system.

6. Frequent Customer Complaints

There are not that many customer reviews yet for the RKIN U1. However, we’ve read about malfunctioning systems and problems with customer service, the warranty or the satisfaction guarantee.

We did not experience these issues firsthand.

Bottom Line: Pricey & Underwhelming (3.62/5.00; U1-W: 3.66/5.00)

Filtration weighted at 60%, and usability and cost at 20% each, the RKIN U1 scored a final rating of 3.62 out of 5.00. The U1-W scored 3.66 out of 5.00.

Honestly, it’s kind of a let-down. This system achieved an adequate 3.87/5.00 in our filtration analysis, fully removing 7 contaminants in our lab tests and producing odorless, clean-tasting water. While it has no NSF/ANSI-certified contaminants, it does have limited third-party testing for the reduction of a few impurities.

It’s simple to set up but a pain to refill. The system, including the feed tank, is very large and heavy. Its size makes it unwieldy – expect to spill a bit of feed water into the waste compartment while you struggle to resituate the tank on its base. Plus, the valves tend to leak when emptying the wastewater. Filter changes, on the other hand, are easy.

It lacks a carafe for instantly accessible water, and dispensing speed for hot, cold, and ambient water is very slow. Volume presets and customization offset this somewhat, though there are so many options – for temperature, too – that it feels a little overwhelming at first.

The RKIN dispenses enough water that is sufficiently hot for most uses, even if it doesn’t reach its advertised top temp of 212 °F. It also produces refreshingly cold water, but only about 2 cups at a time. Still, dispensing is easy and splash-free.

Plus, the convenient U1-W app acts as a remote extension of the nice touch screen display, offering all the same functionality as the physical control panel. In addition, you can monitor filter life and pure water TDS readings.

Finally, other useful features up the RKIN’s appeal: a modern appearance, sturdy build, hot water child lock, remineralization, filter/water change indicators, a UV light for cold water, and 1-year satisfaction guarantee. You can even activate and monitor hydrogen infusion.

However, given its higher wastewater and well above-average upfront and substantially-above average ongoing costs, we feel there are better countertop RO systems providing ambient/hot/cold water.