Editorial Guidelines

Our Review Process

To illustrate our methodology, we’ll use our countertop water filter comparison as an example. Below, you’ll find a detailed breakdown of each step in our product review process and an explanation of how we develop our recommendations – giving you full insight into the most critical part of our work.

Note: For readability, we refer only to “products” below, but every step applies equally to services.

Step 1: Researching & Selecting the Right Product(s) to Review

We always try to evaluate a variety of products from all price segments, because price is obviously an important factor when reviewing any home water treatment equipment. But in our opinion it’s not the be-all end-all. For a holistic approach we also take into account other and oftentimes more crucial criteria while ignoring unnecessary bells and whistles. And so because we want our reviews to represent a selection of the best products available, we start by defining the crucial criteria first and pick our products based on that.

Side note: We also like to review products that are popular in their respective category which we determine by checking Google search volume and Amazon best seller lists.

With our initial list in hand, we conduct due diligence on each item. We review product manuals, descriptions, performance data sheets, warranty terms, third-party certification sites, and even talk to some of the companies directly. We also like to rely on third-party customer ratings and reviews whenever possible as we might stumble upon one or more product aspects that we haven’t considered yet. That said, scanning third-party reviews also involves identifying and ignoring fakes which can be challenging due to the rise of AI.

Finally, we compile all relevant attributes into a draft comparison table. For countertop water filters, that draft includes:

• Upfront price and long-term cost – We check pricing information for all filters on the same day. Ongoing discounts are taken into account whereas short-term sales are ignored. As for long-term filter replacement cost, we base this on average filter life as claimed by the manufacturers and a yearly consumption of 500 gallons of filtered water. Bulk discounts for replacement filters are taken into account, too. For both upfront and long-term cost, our information is usually based on each company’s suggested retail prices found on the official websites or amazon.com.
• NSF certifications for contaminant reduction – These are most important to us as they’re 100% independent and testing against NSF standards is highly standardized. We check the NSF International database, the IAPMO R&T database, and the WQA database. If we do find a certification we check for the (types of) impurities covered and missing. We also check performance data sheets if provided.
• NSF testing and other test data – We also take a company’s own test data into account – with caution, because this kind of testing often only accounts for the beginning of the filter life and it is not always independent.
• Filtration process – We check each countertop filter’s exact filtration process meaning filter media and methods used.
• Filter life indicators
• Product warranty and satisfaction (money-back) guarantee – We read the actual terms.
• Made in USA or similar
• Third-party customer feedback – We check each countertop filter’s third-party ratings on amazon.com, walmart.com, and the company’s own website. We may also check homedepot.com and similar sites. We take all the information in but focus on frequently upcoming issues.
• Additional product aspects – Such as dimensions, feed and filtered water tank size(s), child safety locks for hot water, etc.

Step 2: Getting Our Hands on the Products

The next step is to get our hands on all the products on our list. To manage costs, we typically request free samples from manufacturers. If our request is declined (which frequently happens), we purchase the product ourselves, always directly from the manufacturer or an authorized dealer to ensure authenticity and avoid counterfeits.

Needless to say, we only test products that are brand-new unless explicitly noted otherwise.

Step 3: Testing

During this phase, we complete our initial comparison table by thoroughly testing all aspects that require hands-on evaluation.

Generally speaking, to ensure comparable results we adhere to standardized testing procedures. What’s more, with years of experience and a ton of research under our belts, our methods are continually refined to achieve the most accurate results possible.

Continuing our countertop water filter example:

• Usability – Evaluating initial installation, filter priming, day-to-day use, and ease of maintenance (particularly filter replacement). We also assess build quality, durability, and materials used (more info below).
• Lab testing – We conduct our own lab testing sending water samples to a professional and independent lab in order to determine each filter’s real-life contaminant reduction capabilities (more info below).
• Taste & odor test – Using freshly filtered water (more info below).
• Speed tests – Depending on the type of countertop filter, we measure filtration or dispensing speed (more info below).
• Wastewater test – We measure how much wastewater each countertop reverse osmosis systems produces per 1 gallon purified (more info below).
• Scope of delivery – We check the package for additional tools and components like filter wrenches and faucet adapters.
• Looks – This is more important than you might think because, after all, a countertop water filter will sit on your countertop all day.

Usability

When testing usability, we mimic normal everyday use in order to get plenty of hands-on experience.

First, we set up each product exactly as described in the instructions, carefully noting any issues or standout features. After the initial setup (which, for countertop filters, involves filter priming), we use and maintain each system just like a typical consumer would—including replacing filters when needed.

To keep things consistent, testing for each product category is always carried out by the same team member. This way, we ensure our results stay as accurate and comparable as possible.

Lab Testing

The idea behind our lab testing is to compare the level of impurities in our tap water before and after treatment. So whenever it makes sense we send water samples to a professional and independent lab for analysis. For countertop water filters, this testing shows us exactly how effective each filter is at removing contaminants in real-life conditions.

We currently use two trusted lab testing services: ETR Labs (Environmental Testing and Research Laboratories, Inc.) with their Premium Water Test and Tap Score’s Advanced City Water Test. Both services evaluate more than 100 different water analytes and parameters, including:

• General water quality indicators (e.g., pH, total dissolved solids, hardness)
• Bacteria (e.g., total coliform, fecal E. coli)
• Metals (e.g., lead, iron, chromium, aluminum, arsenic, uranium)
• Minerals (e.g., calcium, zinc, magnesium)
• Anions (e.g., fluoride, nitrate, nitrite)
• Radon
• Potentially harmful organic compounds (e.g., benzene and other industrial solvents; chloroform and other disinfection byproducts; dichlorodifluoromethane and other refrigerants and coolants)

Important: We always cover the full cost of lab testing ourselves and neither the company/brand of the product in question nor we can influence the outcome. This independence makes the lab results highly objective and trustworthy. We also openly publish all lab reports, so you can review the data yourself and draw your own conclusions.

How We Take Samples

We follow a strict protocol taking each water sample:

As mentioned before, all products are brand-new when tested. After carefully setting up each one according to its manual, we collect two samples: one from our untreated tap water, and another from the filtered water. Samples are always shipped to the testing labs on the same day.

To ensure consistency, we typically test all products within a single category using the same water source. For instance, Sara tested nearly all countertop water filters from her home in San Antonio, Texas.

Evaluating the Lab Reports

Once the lab results arrive via email, we carefully review and compare them. Specifically, we look at how the impurity levels and water quality parameters differ between the untreated (raw) tap water and the filtered water. Where needed, we calculate the percentage reductions or increases – for instance, how effectively a countertop water filter removes specific contaminants. Occasionally, lab results reveal new impurities in filtered water that weren’t present in the original tap water, and we highlight those findings as well.

How do we decide which impurities or parameters matter most and which can be safely ignored? That depends entirely on the type of product we’re reviewing. For example:

• Water softeners: The primary goal is reducing water hardness, so we focus on calcium and magnesium levels.
• Water filters (like countertop models): Their main purpose is usually removing potentially harmful contaminants. Here, we reference the strictest available public health goals or guidelines, often from sources like OEHHA, EWG, EPA, or WHO. Sometimes, we also check standards set by state health departments or even international guidelines from countries like Canada. Aside from that, some impurities aren’t harmful but can cause aesthetic issues above a certain threshold so we consider these as well.

Calculating a Lab Score

Finally, we use our in-house tool to calculate a lab score. Essentially for each countertop filter,

• full points are awarded for 100% reduction rates of undesirable impurities.
• fewer points (or none) are awarded for lower or no reduction.
• points are deducted if the treated water shows considerable increased concentrations or introduces new harmful impurities.
• the highest possible lab score is 5.00, the lowest is 0.00.

Note: A 100% reduction means an impurity is no longer detectable above the laboratory’s minimum detection level – the lowest concentration that the testing lab can confidently measure.

Batched Sampling

When testing multiple products of the same type, we usually sample in batches whenever possible. This approach allows us to take just one untreated water sample instead of several, significantly reducing costs, considering each test kit costs around $250.

Below are three examples demonstrating how we batch-sampled different countertop water filter types:

Countertop Reverse Osmosis Systems

We sampled the following countertop RO systems in one batch: AquaTru Carafe, SimPure Y7P-BW, APEC ROCT-PLUS, Frizzlife WB99-C, Bluevua RO100ROPOT, NU Aqua 4-Stage Countertop Reverse Osmosis System

Sampling procedure:

1. Each system was properly set up, primed, and emptied.
2. We simultaneously ran one filtration cycle through each system to avoid TDS creep, discarding the resulting water.
3. We filled a large bucket with raw tap water, stirring thoroughly to evenly distribute impurities.
4. Using a measuring cup, we poured exactly ¼ gallon into each countertop RO system, ensuring there was sufficient water remaining in the bucket to maintain even sediment distribution.
5. We allowed the water to fully process through each system.
6. For each system, we dispensed 1 cup of cold water (discarded) before collecting our filtered water sample directly from the system.
7. The untreated water sample was collected directly from the bucket.
8. All samples were shipped to the lab on the same day.

Gravity Water Filters

We sampled the following countertop gravity water filters in one batch: Big Berkey, Purewell, British Berkefeld (with Doulton Ultra Sterasyl Filters), ProOne Traveler+ (with Old G2.0 5″ Filter), Waterdrop King, Alexapure Pro, Santevia Gravity Water System

Sampling procedure:

1. Each filter was properly set up, primed, and emptied.
2. We filled a large bucket with raw tap water, thoroughly stirring to distribute impurities evenly.
3. Using a measuring cup, we poured the exact same amount of water into each gravity filter, ensuring enough remained in the bucket for consistent impurity levels.
4. We allowed the water to fully filter through each filter.
5. Filtered water samples were taken directly from each filter without intermediate containers.
6. The untreated water sample was taken directly from the bucket.
7. All samples were shipped to the lab on the same day.

Regular Countertop Water Filters

We sampled the following regular countertop water filters in one batch: Aquasana Clean Water Machine, ZeroWater 32-Cup Ready-Read Dispenser, Waterdrop ED04, Waterdrop WFD-22L, PUR PLUS 30-Cup Dispenser, Brita Ultramax Water Dispenser (w/ Elite Filter), Brita Hub Countertop Water Filter System

Sampling procedure:

1. Each system was properly set up, primed, and emptied.
2. We filled a large bucket with raw tap water, stirring well to distribute impurities evenly.
3. Using a measuring cup:
   • We poured exactly ¼ gallon into the Waterdrop WFD-22L Dispenser, PUR PLUS 30-Cup Dispenser, ZeroWater 32-Cup Ready-Read Dispenser, and Brita Ultramax Water Dispenser (Elite Filter), and waited until filtration was complete before taking filtered water samples directly from each dispenser.
   • We poured exactly 1.5 quarts into the Aquasana Clean Water Machine, Brita Hub Countertop System, and Waterdrop ED04 Electric Water Filter Pitcher. We dispensed and discarded the first 2 cups from each system, then collected filtered water samples directly from the units.
4. The untreated water sample was taken directly from the bucket.
5. All samples were shipped to the lab on the same day.

Additional Testing

Aside from lab testing, we conduct several additional hands-on tests tailored specifically to the type of home water treatment product we’re evaluating.

For countertop water filters, this typically includes taste & odor tests, filtration speed measurements, and pure-to-drain ratio tests (for countertop reverse osmosis systems only).

Taste & Odor Test

We assess freshly filtered water and categorize results into 1 of 5 ratings:

1. Pleasant mineral taste, free of any odors
2. Clean taste and odor
3. Slightly improved taste and odor – but not perfect
4. No improvement at all
5. Taste and odor actually got worse

Speed Tests

Depending on the filter type, we measure either filtration or dispensing speed:

Countertop RO Systems

We measure how quickly each countertop RO can dispense 12 ounces (1.5 cups) of filtered water.

Note: Take these results with caution, since some systems filter water on demand, while others pre-filter and store water for immediate dispensing.

Gravity Water Filters

We pour exactly 2 gallons of water into each gravity filter and measure how long it takes until we can dispense 4 cups of filtered water.

Regular Countertop Water Filters

Type 1: For the Aquasana Clean Water Machine, Brita Hub Countertop Water Filter System, Waterdrop ED04, Waterdrop CTF-01, and iSpring CKC1C, we measured the time it took each filter to dispense exactly 12 ounces of filtered water.

Type 2: For the Waterdrop WFD-22L Dispenser, PUR PLUS 30-Cup Dispenser, ZeroWater 32 Cup Ready-Read Dispenser, and Brita Ultramax Water Dispenser w/ Elite Filter, we completely filled each feed-water tank and measured how long it took until we could dispense 12 ounces of filtered water.

Wastewater Test

For countertop reverse osmosis systems (and any other type of RO), we measure wastewater output. Specifically, we test how much purified water each system produces compared to how much water it wastes.

Exact testing procedure for countertop ROs:

1. We empty all water tanks.
2. We fill the feed water tank to the max line, carefully measuring the exact amount added.
3. We dispense as much filtered water as possible and until the flow stops and/or the system prompts a refill. For systems offering various temperature settings, we dispense all available cold, ambient, and hot water.
4. We measure the volumes of purified water and wastewater separately.
5. We calculate the final pure-to-drain ratio.

Step 4: Rating and Ranking

Finally, it’s time to rate and rank the products we’ve tested. Continuing with our countertop water filter example, we rate and rank products across three main categories (each scored from 0.00 to 5.00, with 5.00 being the highest):

1. Filtration – We start with the lab score calculated in step 3 and then adjust by adding or subtracting points based on NSF certifications, additional contaminant reduction test data, and the results of our taste & odor tests.
2. Usability – This is a more qualitative rating covering the initial setup, daily ease of use, maintenance (particularly filter replacements), and results from our filtration or dispensing speed tests.
3. Costs – We use an in-house algorithm to assess each product’s value relative to the average cost of comparable products (for example, countertop RO systems with hot water functionality). During this calculation, we adjust the upfront price of a product if a company has provided us with a discount code. However, if getting a discount requires some kind of subscription, then this doesn’t count in our evaluation. Also, we may adjust expected annual filter replacement expenses if a manufacturer’s stated filter lifespan appears unrealistic.

For our final rating, we apply the following weighting:

• Filtration: 60%
• Usability: 20%
• Costs: 20%

Additionally, we factor in third-party customer feedback, as well as any unique features, benefits, or issues we hadn’t previously considered.