The Waterdrop A1 delivers excellent contaminant reduction and convenient hot-and-cold RO water, but lacks built-in remineralization and only holds certification for TDS reduction. In our testing, it produced exceptionally clean water with strong overall performance. It’s a great fit for folks who want premium features and don’t mind adding their own minerals.
What We Like
What We Don’t Like
| Price | $650 |
| Contaminants Reduced | 10+ |
| Certifications | NSF/ANSI 58 |
| Process | Mechanical + Carbon + RO + UV |
| Filter Capacity | CF filter 225 gal.; RO membrane 550 gal. |
| Annual Cost | ~$130 |
| Warranty | 1 year |
We wanted to know how this system compared to the other countertop reverse osmosis units we’ve tested, including AquaTru (currently the top-scoring model) and RKIN. To find out, we conducted our own series of performance tests, combining objective data from Tap Score’s testing lab with our own subjective assessments across a range of performance categories.
Table of Contents
📊 Scoring Data
We use six key performance assessments to test all the water filters we review, awarding scores in each category based on our lab data and personal experience. We tested the Waterdrop A1 along with a handful of the other most popular countertop water filter systems, then compared their performance and ranked them based on their overall weighted scores.
Each performance category is scored based on several criteria, including sub-categories of contaminant reduction, component quality, servicing requirements and costs, the presence of performance & design certifications, and the manufacturer’s warranty, shipping, and returns offerings. We’ve shared the Waterdrop A1’s scores in the table below.
| Criteria | Results |
|---|---|
| Overall Score | 9.12 |
| Health Related Contaminants | 9.80 |
| Aesthetic Related Contaminants | 8.00 |
| Performance Certification | NSF/ANSI 58 |
| Filtration Rate | 0.042 GPM |
| Component Quality | Excellent |
| Component Certification | Exceptional |
| Setup | Fair |
| Servicing Requirements | Exceptional |
| Costs | $0.269/ gallon |
| Warranty Length | 1 year |
| Shipping | Free to contenental US |
| Returns | 30 days |
🚰 Contaminant Reduction
Score: 9.42Reverse osmosis filters are known for offering one of the most comprehensive water treatment solutions, using a purification process that’s capable of greatly reducing or removing the majority of contaminants. This makes them generally more expensive than non-RO filters.
With a high upfront investment (it costs $650 at the time of this review), the Waterdrop A1 definitely needs to meet or exceed its performance claims. We used Tap Score lab testing to analyze which contaminants it could remove from our water and its overall water quality effects.
Our scoring in this category is also influenced by performance certifications, which manufacturers can use to demonstrate that their products reduce contaminants as advertised.
Our Performance Testing
Score: 9.62
We took two samples of water* for our Waterdrop A1 test:
- One sample of unfiltered water
- One sample of purified water directly from the A1
These samples were then sent to Tap Score for laboratory testing. After several days, we received an email with a link to view the two digital reports (one for each water sample) on the SimpleLab platform.
All the contaminants we’re discussing next were detected with Tap Score’s lab testing, with the exception of chlorine. Since chlorine is a volatile contaminant and dissipates from water quickly, we used chlorine test strips to detect this chemical on-site.
We measured all our data against the Health Guideline Levels (HGLs) rather than the EPA’s Maximum Contaminant Levels (MCLs), since HGLs are more stringent and health protective.
Health-Related Contaminants
Score: 9.70
Our baseline water contained 10 contaminants with possible health effects, including 0.032 PPM uranium (exceeding the HGL of 0 PPM) and 1.4 PPM fluoride (exceeding the HGL of 0.799 PPM).
| Analyte | Type | Unit | Pre | Post | Difference |
|---|---|---|---|---|---|
| Alkalinity (as CaCO3) | Properties | PPM | 81 | 9 | -88.89% |
| Barium | Metals | PPM | 0.031 | 0.0055 | -82.26% |
| Bicarbonate | Minerals | PPM | 98.37 | 10.99 | -88.83% |
| Calcium | Minerals | PPM | 26.9 | 0.5 | -98.14% |
| Carbonate | Minerals | PPM | 0.18 | 0.0016 | -99.11% |
| Chloride | Inorganics | PPM | 13.5 | 0 | -100.00% |
| Chloride-to-Sulfate Mass Ratio | Properties | 1.59 | 0 | -100.00% | |
| Copper | Metals | PPM | 0.0654 | 0 | -100.00% |
| Fluoride | Inorganics | PPM | 1.4 | 0 | -100.00% |
| Grains per gallon | Properties | Grains | 5.55 | 0.073 | -98.68% |
| Hardness | Properties | PPM | 94 | 2 | -97.87% |
| Hardness (Ca,Mg) | Properties | PPM | 94 | 2 | -97.87% |
| Hardness (Total) | Properties | PPM | 94.94 | 1.25 | -98.68% |
| Langelier Saturation Index | Properties | -0.66 | -4.3 | 551.52% | |
| Magnesium | Minerals | PPM | 6.58 | 0 | -100.00% |
| Molybdenum | Metals | PPM | 0.006 | 0 | -100.00% |
| Nitrate (as N) | Inorganics | PPM | 2.6 | 0.2 | -92.31% |
| pH | Properties | pH | 7.6 | 6.5 | -14.47% |
| Phosphorus | Inorganics | PPM | 1.1 | 0 | -100.00% |
| Sodium | Minerals | PPM | 10.7 | 1.22 | -88.60% |
| Sodium Adsorption Ratio | Properties | 0.48 | 0.47 | -2.08% | |
| Specific Conductivity | Properties | umhos/cm | 234 | 7.2 | -96.92% |
| Strontium | Metals | PPM | 0.144 | 0 | -100.00% |
| Sulfate | Inorganics | PPM | 8.5 | 0 | -100.00% |
| Total Dissolved Solids | Properties | PPM | 138 | 6 | -95.65% |
| Uranium | Metals | PPM | 0.0322 | 0 | -100.00% |
| Zinc | Metals | PPM | 0.248 | 0 | -100.00% |
The contaminants not exceeding the HGL were sulfate, zinc, strontium, molybdenum, barium, nitrate, phosphorus, and copper. Exposure to high concentrations of these contaminants has been linked to health effects including gastrointestinal, liver, and kidney problems, skeletal and developmental issues, and cancer.
Our filtered water results showed that the A1 achieved complete removal of nearly all detectable metals and inorganics, including copper, molybdenum, fluoride, phosphorus, sulfate, strontium, and uranium. This outcome is consistent with the performance of a true reverse osmosis membrane system.
Barium was reduced by 82.26%, from 0.031 PPM to 0.0055 PPM, while nitrate concentrations decreased by 92.31%, from 2.6 PPM to 0.2 PPM. These were the only two contaminants with health effects that weren’t completely eliminated.
In our on-site tests, the A1 also eliminated chlorine (down from around 2 PPM).
Aesthetics, pH, and Mineral Content
Score: 8.00
While the A1 did improve our water aesthetics (taste and smell) by removing chlorine, its score in this category was pulled down by the demineralization outcomes of the purification process.
Hardness minerals and alkalinity were almost completely removed:
- Calcium was reduced by 98.14%, from 26.9 PPM to 0.5 PPM.
- Bicarbonate was reduced by 88.83%, from 98.37 PPM to 10.99 PPM.
- Carbonate: reduced by 99.11%, from 0.18 PPM to 0.0016 PPM.
- Magnesium was completely eliminated, from 6.58 PPM to 0.0 PPM.
This resulted in a total hardness reduction of 98%, from 94 PPM to less than 2 PPM. Sodium was also reduced by 88.6%, from 10.7 PPM to 1.22 PPM.
Since many of these minerals contribute to alkalinity, the pH of our water unsurprisingly dropped from 7.6 to 6.5, and the Langelier Saturation Index shifted sharply negative (–0.66 → –4.3), confirming aggressive demineralization and higher corrosivity.
Total Dissolved Solids (TDS) and conductivity were reduced by >95%, telling us that our water had been essentially purified.
These are all normal outcomes for a reverse osmosis system, since the RO process thoroughly removes the majority of dissolved solids from water, including minerals and ions that contribute to alkalinity.
However, other countertop RO systems we’ve tested use an included remineralization media that reintroduces some of these lost minerals and makes the purified water more alkaline. The A1 doesn’t have this feature, and there’s no option to swap out a filter for one with remineralization capabilities, as we’ve seen with other models.
That’s quite disappointing, meaning that if you want to remineralize your water for taste and health benefits, you’ll need to use your own mineral drops or alkalizing water filter pitcher to treat your purified water.
Quick Summary: Does the A1 Have Remineralization?
| Feature | A1 Countertop RO | Most Competitors |
|---|---|---|
| Built-in Remineralization | ❌ No | ✔ Yes |
| Alkaline Water Output | ❌ No | ✔ Often 7.5–9+ pH |
| Swap-In Mineral Filter Option | ❌ None available | ✔ Sometimes |
| Requires After-Treatment? | ✔ Yes | ❌ Not usually |
Performance Certifications
Score: 8.00
We know that many folks find performance certifications reassuring when they’re deciding whether or not to invest in a water treatment system, especially one that costs a lot of money.
These are optional and involve professional lab testing by the NSF, WQA, or IAPMO to determine a filter’s ability to reduce specific contaminants as claimed by the manufacturer.
There are numerous NSF Standards that a water filter can be certified to, but for reverse osmosis systems, the most appealing Standard is NSF 58, since this is specifically for RO units and covers a broad spectrum of contaminants, from chemicals to heavy metals, radioactive contaminants, and everything in between.
Very few countertop RO systems that we’ve tested have obtained official certifications. While the A1 has been IAPMO certified to NSF 58, it’s only for TDS reduction, and the filter isn’t certified for any of the other contaminants it’s claimed to reduce. That resulted in a score of 8.00 in this category—not the highest, but definitely still room to improve.
🚦Filtration Rate
Score: 7.00As with all the pressurized systems we test, we measured the Waterdrop A1’s flow rate in gallons per minute (GPM). It’s one of the slowest-filtering countertop RO systems we’ve used so far, with a flow rate of 0.042 GPM based on its time to filter a full tank of water (4 minutes and 40 seconds).
Efficiency Ratio
Only reverse osmosis systems have an efficiency ratio*, so it’s not a factor that influences our standardized water filter scoring system. But it’s still important to discuss, since it directly affects how much water is wasted, as well as how much energy is used, per gallon of water purified.
The A1’s pure-to-wastewater ratio is 2:1, meaning that only 1 gallon of water is wasted for every 2 gallons of purified water produced.
Is this the most efficient countertop RO system we’ve ever seen?
No – that title goes to AquaTru, which has a 4:1 performance efficiency. Many of the other systems we’ve tested have 3:1 efficiency ratios, so while the A1 is efficient enough, it’s not the best we’ve come across.
📐 Design
Score: 9.40The Waterdrop A1 didn’t blow us away with its design quality, but it does have a certification for lead-free construction, which pulled its score up in this category.
The unit is pretty conventional in appearance and size for a countertop RO system, its pretty big and heavy (it measures 18.3 by 7.8 by 17.1 inches). It has two water tank capacities:
- A room temperature internal tank capacity of 750 ml
- A cold water internal tank capacity of 1L
The idea is that you plug it into a power outlet and have it sitting on your countertop as a permanent fixture (except without the permanent install!), so you can quickly access purified RO water in the same way that you’d use your kitchen faucet.
And it takes a couple hours for the cooling functionality to be ready after plugging it in, so it’s not one that should be unplugged or moved around a lot.
The unit has a modern black and grey design that should fit nicely in most kitchens, although it is quite bulky, so it might not be ideal for homes with limited counter space.
Component Quality
Score: 8.50
The Waterdrop A1 is made from BPA-free, food-grade plastics. We emailed Waterdrop to ask exactly what types of plastics are used, since this information is available from other manufacturers. Unfortunately, Waterdrop replied to say that they can’t publicly disclose additional material details due to “proprietary reasons”.
Some folks may have issues with using a water filter that’s mostly made from plastic, especially when the purified water is stored in a plastic container. This is something you’ll need to consider when you’re deciding whether this type of countertop RO system is right for you.
We’ve only tested a couple RO systems with glass water collection containers so far: the AquaTru Carafe (currently the highest-scoring system and the only product to receive a 10.00 for component quality) and Bluevua.
Filter Materials
The A1 contains two physical filter cartridges, which provide a total of seven stages of filtration. These are:
- A CF Filter (Composite Filter), which combines PP cotton, a carbon block made from coconut shell, and a scale inhibitor.
- An RO Filter, which contains a non-woven fabric layer and the reverse osmosis membrane, which removes contaminants as small as 0.0001 micron.
Most of these filter materials are commonly used in water filters, with the RO membrane being exclusively found in RO systems. A couple of filter stages mentioned (the “scale inhibitor” and “non-woven fabric” layer) aren’t elaborated on, and if we’re being cynical, are potentially just mentioned to bulk up the number of filtration stages to an impressive seven.
The final two stages involve dual UV light sterilization within the internal water tanks, which are said to have a 99.9% sterilization rate. UV sterilization shouldn’t be used to kill bacteria in your water supply; rather, it’s there to prevent the buildup of microorganisms in the water tanks.
Tech Design Features
Like many modern countertop RO systems, the Waterdrop A1 has a few helpful and impressive tech design features that are worth mentioning.
There’s a digital display screen on the front of the unit that features a filter life reminder, a TDS monitor (helpful for checking the filters’ performance), six water temperature presets, and five water volumes (so you can choose the amount of water to dispense in a single button press).
A big perk of the A1 is that it can provide purified hot and cold water on demand. It has a temperature range from 41℉ to 203℉, so if you want to use RO water in your hot beverages, you won’t have to boil it separately. The system’s built-in heating elements can heat water in just a few seconds.
The display screen also features a child lock (important since it dispenses hot water) a couple of energy-saving modes, altitude mode, and filter life trackers.
Materials Safety Certification
Score: 10.00
The Waterdrop A1 is certified for lead-free materials by IAPMO and holds materials safety certification as part of its NSf/ANSI 58 certification.
⚙️ Setup
Score: 8.00Setup is generally a quick and easy process for countertop RO units like the A1 because there’s no complex plumbing work required. You can simply place it on a countertop and follow the basic assembly and filter flushing instructions in the user manual.
That said, the A1 received the worst setup score of all the counter reverse osmosis systems we’ve tested so far, and there were a couple of reasons for this:
- While the flushing process* is all automated, you have to manually empty and refill the water tanks throughout the process.
- This process wasn’t quick. It took just over 41 minutes from start to finish (Waterdrop is overly optimistic with its 30-minute estimation in the user manual). Since we had to empty and refill the tanks, we couldn’t simply do something else while we waited for the process to complete.
We did appreciate the countdown on the display screen, which showed exactly how long remained and when the process was complete.
🔧 Maintenance
Score: 10.00The A1 is both affordable and easy to maintain, earning it the highest score possible in the maintenance category.
Servicing Requirements
10.00
The main servicing task for the A1 is replacing the two filters. This keeps the system performing properly. Without filter replacements, the existing cartridges would eventually become clogged, lose their contaminant reduction efficiency, and potentially even degrade, releasing trapped contaminants back into the water.
The digital display screen has a filter life tracker, with alerts that notify you when a new filter is needed, so there’s no chance of forgetting and no need for you to track lifespans yourself. We also appreciated having just two filter cartridges to change, since most countertop RO systems have at least three.
Aside from replacing the filters, Waterdrop also recommends flushing around 1-2 tanks of water through the machine whenever you haven’t used it for three consecutive days. There’s an included brush for cleaning, and the drip tray, tanks, and unit exterior should all be cleaned with warm water and mild soap as necessary.
Costs
Score: 10.00
We calculated the A1’s ongoing costs by working out the cost-per-gallon of each filter cartridge, then combining them to get a total. The unit has a low maintenance cost of just $0.269/ gallon based on the following breakdown
| Filter | Cost | Capacity (gal.) | Cost per gallon |
|---|---|---|---|
| RO filter | $59.99 | 550 | $0.109 |
| CF filter | $35.99 | 225 | $0.16 |
It’s one of the most affordable-to-maintain countertop RO systems we’ve tested, with the CF filter lasting for 225 gallons, or around 6 months, and the RO membrane lasting for 550 gallons, equating to around 12 months.
🏢 Company
Score: 8.65Waterdrop’s returns, warranty and shipping policies are about industry standard from what we typically see.
Warranty
Score: 8.50
The Waterdrop A1 is backed by a 1-year warranty against any manufacturing defects that occur during the warranty period. Under this warranty, you’ll be entitled to free returns, repair services, or replacements, depending on the issue you’re dealing with.
You can find warranty information on this page.
Shipping
Score: 9.50
All Waterdrop products are shipped with Economy Shipping (regardless of your total spend), and delivery is available to most US states. Waterdrop currently doesn’t ship to Alaska, American Samoa, Hawaii, Guam, Marshall Islands, Micronesia, Northern Mariana Islands, Palau, Puerto Rico, or the U.S. Virgin Islands.
You may choose to upgrade to Standard Shipping if you want faster shipping, which doesn’t cost any extra if your order is over $200. There’s also Express Shipping, which incurs an extra fee.
View Waterdrop’s shipping policy here.
Returns
Score: 8.00
If you receive the A1 and are dissatisfied for any reason within 30 days of your purchase, you’ll be able to return it for a refund under Waterdrop’s 30-day return policy. There are a couple of things to note:
- The product should be disassembled and returned in its original packaging
- You’ll need to cover the return shipping cost.
Any returns made after this window will be subject to a 10% restocking fee as well as the return shipping cost.
Here’s Waterdrop’s returns policy for more information.
💰 Value For Money
Overall, we think the Waterdrop A1 is a solid choice for a countertop reverse osmosis system, performing well in our testing and ticking our boxes for ease of use and ongoing affordability.
The only factor that we think will put a lot of people off is upfront price. Waterdrop regularly offers discounts, but the official price tag is just under $650. Yes, you do get a lot for the investment, including purified RO water at any temperature, a modern design, a host of fancy presets, and built-in UV sterilization. But there’s no included remineralization (not even an optional upgrade), and the system is only certified to reduce TDS, so it’s worth weighing up the value of the hot water dispensing against the features that are missing.
If hot water dispensing isn’t that big of a deal, I recommend looking at the AquaTru as another option. It’s around $250 cheaper and is the only countertop RO system we’ve tested so far that’s certified for every single contaminant it’s claimed to remove.
Alternatively, if money is an issue but you like the Waterdrop brand, it’s definitely worth checking out the N1, another Waterdrop model that’s half the cost of the A1 and received the exact same overall score in our testing.
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