How We Test Faucet-Mount Water Filtersv1.0

Matthew Lee
Reviewer
Lap Vo
Test Lead
Nguyen Ntk
Visual Specialist
Updated

Water filtration equipment has become an essential part of the home for many households. Surveys have also revealed that as many as 77% of Americans are now filtering their water instead of relying on public utility companies to do it for them.

Given multiple high-profile cases of water contamination across the country, it's easy to understand why people are shifting towards a DIY approach to water filtering.

One of the cheapest yet most efficient kinds of water filtering equipment that you can use is faucet-mount water filters. They attach directly to your faucet and provide your home with on-demand clean, potable water.

To help you buy the best filter possible and show you how the testing process is done for each review article we have on our website, you'll find the full testing procedure for faucet-mount water filters in this Healthy Kitchen 101's feature!

Eight faucet-mount water filters arranged in two rows, with the water testing kit and sampling vials in the middle.

Testing Methodology

To ensure consistency and reliability in our testing, we perform the same testing procedure across all faucet-mount water filters. This will ensure that our test data are comparable across the board.

Additionally, the testing methodology will be subjected to changes in the future. It can be changed for any reason, from our team finding new ways to test the product better, or there are changes in the market that require us to revamp our testing procedure.

In any case, if there are any changes — no matter how small — we’ll update our pages and inform you accordingly.

How We Test Our Faucet-Mount Water Filters

Overall Rating

The overall rating of a faucet-mount water filter is calculated by aggregating the scores of three major tests: Performance, Design, and Ease of Use. Each test has a different weighting in the calculus, depending on how important it is to the user.

Here’s the breakdown.

  • Performance (50%)
  • Design (20%)
  • Ease of Use (30%)

Performance

In the performance test, we put the faucet-mount water filter through its paces on our testing rig. The filtered water is collected in a cup, then it’s tested using specialized testing kits.

Since this section showcases how well the filter actually performs, it is the most important test in our methodology. It’s also the reason why the performance test takes up 50% of the overall rating.

Currently, the performance test is separated into four smaller tests:

  • Chlorine test (40%)
  • Flow rate test (60%)

Chlorine Test (40%)

The Premise

Chlorine is a common disinfectant that public utility companies use to kill bacteria and viruses in the water. Though it’s not harmful to drink (at least in concentrations that are usually found in public tap water), chlorine can impart an off-taste or odor to the water.

By removing chlorine from the water, faucet-mount filters can restore tap water's “pure” taste.

Eight test sticks arranged in a row, displaying results corresponding to the water sample vials collected from eight filters.
Testing sticks corresponding to eight vials of filtered water sampled from the latest batch of faucet-mount filters. A test stick showing the reading for the chlorinated water we used to test the filter is to the right, along with the color chart.

Testing Procedure

The faucet is first mounted onto the faucet of our testing rig.

As our tap water is not sufficiently chlorinated to show clear results, we decided to mix a testing solution on our own by impregnating 2.6 gallons (equivalent to 10 liters) of water with a small amount of Calcium Hypochlorite (Ca(OCl)2).

Ca(OCl)2 will dissolve and turn into Chlorine in water.

Using a small pump, we feed the water through the testing rig and the filter. 

The filtered water is collected in a cup and tested to see how drastically the chlorine level has changed compared to the original chlorinated water using a testing kit.

Scoring

We’ll score the chlorine-filtration performance of each filter based on the coloring of the testing kit.

Test result being taken from a filtered water sample of the PUR Plus FM2500V faucet-mount water filter.
Testing the quality of the filtered water produced by the PUR Plus FM2500V.
Color chart with used test strips in the center. Vial of sampled water is to the left. Brita Basic filter to the right.
The test strips on the color chart under laboratory lighting.
Center is the color pad with used test strips. To its right is the Wingsol WS-FM001 filter. To its left is a vial of water.
The final test result of the Culligan FM-25 under laboratory lighting.

Flow Rate Test (60%)

The Premise

The flow rate of a faucet-mount filter determines how quickly it can purify and deliver clean water for you. Because the filtration block is made from dense materials that slow down water flow, the flow rate through the filter will be noticeably slower than you can expect from a bathroom or kitchen faucet without it.

In the US, the maximum flow rate of a bathroom or kitchen faucet is 2.2 gallons per minute or GPM. But depending on many factors (water supply in the area, your faucet’s design, etc.), your faucet’s actual flow rate can be anywhere between 1.0 and 2.2 GPM

Testing Procedure

This test aims to measure the difference between the typical flow rate of the faucet and the water flow rate when it goes through the filter. The closer these rates are to one another, the better.

We start by calculating the normal flow rate of our faucet sans filter.

After that, we mount the filter to the faucet and switch it on. The filtered water is deposited into a cup while a timer — set for 20 seconds — runs in the background.

After 20 seconds, the water collected is weighted on a scale.

Scoring

We first convert this amount into gallons as our scale measures in milliliters (ml). The result is multiplied by 3 to get an accurate reading on the GPM of the filter.

If the result is 1.5 GPM or higher, the filter will receive an “Excellent score from us (10 out of 10). For every 0.2 GPM below 1.5 GPM, one point will be deducted.

Any filter with a flow rate lower than 0.5 GPM will be graded as "Failed.”

Design

In the design assessment, our team inspects every component and detail of the filter to see how well it’s built. Since it’s constantly exposed to water, the filter can wear down very quickly if it's not built well.

The design assessment’s results can help you determine how durable and long-lasting the filter is.

Faucet-mount filters have two main components: the filter block and the housing. Also included in the assessment is the routing valve, which is a small component that allows users to alternate between filtered water and regular tap water.

  • Filter Block (50%)
  • Housing (40%)
  • Routing Valve (10%)

Housing (40%)

The housing is the “main body” of the filter. It will either have a compartment for the filter block or a connector so that one can be attached. There is also a fixing collar, which allows you to connect the filter to your faucet.

Both of these components are assessed and scored.

We’ll also look at the housing presentation (aesthetic, materials, etc.)

The Brita Basic faucet-mount water filtration system’s housing, once the filter has been fully assembled.
The silvery, chrome-plated housing of the Brita Basic faucet-mount water filter when fully assembled.

Filter Block (50%)

Responsible for filtering harmful chemicals and contaminants out of the water, the filter block is the most important part of any faucet-mount filter. As a result, it’s the component with the largest score weighting in the design assessment (50%).

Besides assessing how well the filter is constructed, we’ll also look into the filtration materials and longevity of the filter.

The white plastic filter cartridge that comes with the filter. Printed on it are the DuPont logo and the number 100.

Routing Valve (10%)

The routing valve is a small yet crucial component of a faucet-mount water filter. Most filters have two modes: filtering and bypassing.

When in “filtering mode,” tap water will be routed through the filter block and purified. When you don't need filtered water, you can switch the filter to “bypass mode,” allowing tap water to flow without passing through the filter block.

You can switch back and forth between either mode by working the routing valve. This valve is operated manually using a switch located on the filter.

We look at two things in this section: how easy it is to use the valve and how well it’s constructed (by seeing whether it leaks when switching between modes.)

The handle of the PUR Plus FM2500V is in the vertical position, activating the water filtering mode.
The handle of the PUR Plus FM2500V is switched downward. The routing valve will direct tap water through the filter cartridge and produce clean water.

Ease of Use

The ease of use assessment is all about the user experience. In this section, we look at three aspects in particular: the ease of installation (25%), usability (30%), leak (35%), and maintainability (10%).

Installation (25%)

As a whole, installing a faucet-mount water filter is quite easy. The shipping box should contain all the parts (adapters, rubber seals, plumbing tape) you need to install the filter properly. However, certain models can be quite a pain.

We’ll report our own installation experience in this part to give you a better idea of the process.

Usability (30%)

For the usability section, we factor in all aspects of the user experience when using the filter. This includes how straightforward it is to open and close, whether there are any leakage issues when changing modes, and how secure the filter is held in place on the faucet.

Leak (35%)

Faucet-mount filters may leak either from their nozzles or seams on their housing. There are many potential reasons why, from improper installation to ill-fitting adapters or faulty construction. During this assessment, we’ll pay attention to how watertight the components on the filter are and score our observation accordingly.

Maintenance (10%)

Filter blocks have a finite lifespan - they need to be replaced after they have treated a certain amount of water.

Some models come with an indicator light that notifies you when the filter needs to be changed, whereas, for other models, you need to take note of this yourself.

The model will receive a bonus in this assessment if it has a filter change light. We’ll also note how easy it is to switch out the filter and buy replacement filters.