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Our Verdict (Best For)
The Kirkland Signature water filter pitcher removed most contaminants to below MDLs in our lab testing. That, along with the low costs make it a strong value pick. However, the one major drawback is that our filtered water retained some taste. Additionally, while the Kirkland holds NSF certifications for the reduction of 14 contaminants, they primarily address easy-to-remove organics. The company also didn’t provide any reduction rates or additional test data beyond their certifications. On the usability front, the pitcher is lightweight, pours well, filters at a decent speed, and the flip-top lid makes refilling easy, even though it doesn’t fully close. Overall, solid performance for the price.
The Kirkland Signature by Costco is a water filter pitcher. It’s designed for use as a drinking water filter and can purify both tap water and properly disinfected well water.
As usual, we’ve tested the pitcher with our own hands:
- Hands-on experience: We assembled, primed, used, and maintained it.
- Filtration effectiveness: We sent an unfiltered and a filtered tap water sample to a professional lab for analysis in order to determine real-life contaminant reduction capabilities. Plus, we checked for NSF certifications and other test data.
- More testing: We performed a taste & odor test as well as a filtration speed test.
- All other product aspects: We considered initial + long-term cost, product warranties, additional features, frequent customer complaints, etc.
Contents
Final Rating: /5.00
Filtration: /5.00
Usability: /5.00
Costs: /5.00
| Type: | Water Filter Pitcher |
| Price (Jan 20, 2025, No Short-Term Sales): | $29.99 |
| Yearly Cost for 300 gal Based on Rated/Claimed Filter Life (Mar 19, 2024): | ~$30 |
Final Rating: /5.00
What We Like Most
- Filtered water was free from odor.
- High count of NSF-certified contaminants (but limited in regards to contaminant types mostly covering “easier-to-remove” organics).
- Fast filtration speed.
- Easy to assemble, use and maintain; lightweight, pours nicely, and flip top lid makes refilling easy.
- Has a filter life indicator.
- Very affordable upfront cost, which includes a spare filter cartridge, and very low yearly filter replacement fees.
What We Don’t Like
- Some taste remained in our filtered water.
- No information provided on the filter media used.
- Flip top lid doesn’t close all the way.
- Unknown warranty.
- 3rd-party customers complained about taste issues, the plastic that may crack, and leaking filter media.
How the Kirkland Signature Filtered Water Pitcher Compares to…
10 Other Water Filter Pitchers
In this video, Mike highlights our water filter pitcher top picks. The Kirkland Signature was included in our testing achieving the highest lab score, but it didn’t make the cut mainly because the filtered water still had some taste to it.
Please note: Our full guide on the best water filter pitchers is available here.
Video Chapters + Comparison Sheet
- Link to Comparison Sheet
- 00:00 – Intro
- 00:58 – Our 11 Pitchers
- 02:00 – How We Tested & Ranked
- 04:29 – Pitcher Assembly & Filter Priming
- 05:21 – Sampling Process
- 06:18 – Taste & Odor Test
- 06:58 – Speed Test
- 08:28 – Best Overall (Clearly Filtered)
- 12:27 – Best for Usability + Affordability (Waterdrop)
- 15:45 – Best for Bacteria & Cyst (LifeStraw)
- 18:30 – Best for Nitrate (ZeroWater)
- 23:00 – Best for Fluoride
- 23:39 – Summary
Full Analysis of the Kirkland Signature Filtered Water Pitcher
Filtration: /5.00
1. Lab Results: /5.00
Remember that our before vs after lab comparison is not an exact science. It’s informational and subject to variability, inaccuracies, and interferences caused by natural fluctuations in water quality, accidental contamination, human error, instrumentation issues, and more. Furthermore, our lab-testing is limited to those contaminants present in our water supplies and at their respective concentrations. As such, it can only give us a general idea for how effective a certain water treatment product might be.
Lab Results Chart
| Potentially Harmful | Aesthetic Issues | Feed Water Level | Filtered Water Level | Reduction Rate | |
| Water Disinfectants | |||||
| Chlorine (mg/L) | ✖ | ✖ | 0.2 | 0 | 100% |
| Disinfection Byproducts | |||||
| Bromodichloromethane (µg/L) | ✖ | 0.58 | 0 | 100% | |
| Bromoform (µg/L) | ✖ | 0.75 | 0 | 100% | |
| Dibromochloromethane (µg/L) | ✖ | 0.94 | 0 | 100% | |
| Metals | |||||
| Copper (mg/L) | ✖ | ✖ | 0.01 | 0 | 100% |
| Barium (mg/L) | ✖ | 0.01 | 0 | 100% | |
| Boron (mg/L) | ✖ | 0.04 | 0.02 | 50% | |
| Lithium (mg/L) | ✖ | 0.01 | 0.01 | 0% | |
| Strontium (mg/L) | ✖ | 0.18 | 0.02 | 89% | |
| Salts | |||||
| Nitrate (N) (mg/L) | ✖ | 1.65 | 0 | 100% | |
| Fluoride (mg/L) (Flawed?) | ✖ | 0.46 | 0.48* | 4% Increase* | |
| Other | |||||
| Uranium (µg/L) | ✖ | 7 | 0 | 100% | |
| Aesthetic Parameters | |||||
| Hardness (mg/L) | ✖ | 111.9 | 14.5 | 87% | |
| Impurities NOT Detected in Unfiltered Tap Water Sample | |||||
| Silver (mg/L) | ✖ | 0 | 0.01 | ||
| *Due to known interferences of the applied testing method, we assume fluoride levels must be taken with a grain of salt. | |||||
| Full Removal | |||||
| Considerable Reduction | |||||
| Concentration More Than Double of Unfiltered Water Sample | |||||
| Potential Leaching Reached or Exceeded the Strictest Public Health Guideline We Could Find | |||||
*100% means reduction to below the minimum detection level. To learn more about our testing procedures check our editorial guidelines.
Link to Filtered Water Report
Link to Unfiltered Water Report
Usability: /5.00
Costs: /5.00
Please note: This page is still a work in progress. Additional content and details will be added shortly – stay tuned!
About the Author(s)
Mike is a former team member who made his mark by contributing to our first big water filter pitcher comparison video and reviewing a couple POE water treatment systems. Beyond the world of water solutions, Mike is a full-time blogger and YouTuber alongside his wife, Ashley. Together, they’ve transformed their passions into a creative space called Joyfully Growing, where they share DIY tutorials and simple home improvement tips to help others love the homes they’re in.
Raoul has a background in mechanical engineering and has been writing about home water treatment since 2015. He designs our product review processes, analyzes the results, and ties everything together. As editor-in-chief, he tries hard to keep the whole operation running smoothly behind the scenes.