EZ-Change Under-Sink Drinking Water Filter



EZ-Change Under-Sink Drinking Water Filter


Clear, clean, great-tasting water for drinking and cooking is easier to achieve than ever before with the Culligan® family of EZ-Change Drinking Water Filters. The Culligan® US-EZ-4 Premium Under-sink Drinking Water Filter System features a twist-on, twist-off mechanism, quick-Connect fittings, and double water shut-off. The filter reduces bad taste & odor, aesthetic chlorine taste & odor, sediment, lead, cysts such as giardia and cryptosporidium, mercury, turbidity, particulate class I, VOC's, MTBE, and chloramines. The package includes a filter head with a built-in bracket, RC-EZ-4 Premium Filtration replacement cartridge, mounting screws, supply adapter, lead-free faucet with built-in electronic life indicator, 1/4-inch plastic tubing.

Best Price*
Cost Per Gallon*
Total Contaminants Reduced
NSF/ANSI 42, 53, 401
500 gal
Flow Rate (gpm)

Manufacturer’s description on Amazon:

The Culligan US-EZ-4 Premium Easy-Change Under-Sink Drinking Water Filtration System helps keep your family healthy and hydrated by providing clean water through a dedicated faucet (included with system). The Easy-Change Filter fits easily under the sink and can be installed with any sink’s water system tapping into the cold water line to keep fresh water at your family’s fingertips. Designed for convenience, this filter can be installed and replaced in mere minutes with the simple twist-on, twist-off mechanism and built-in quick-connect fittings. There is no need to shut the water supply off when changing the cartridge with the built-in ball and check valve in the filter head.

Key Contaminants Removed:
Pesticides & Herbicides
Other Benefits:
  • 2-year warranty
  • Easy install
  • Electronic filter life indicator

WaterFilterComparisons’ Review

The Culligan US-EZ-4 Water Filtration System is designed to support your household’s health and hydration by delivering filtered water through its faucet, which is included with the product. This under-sink filtration system fits easily beneath the sink and can integrate with any sink by connecting to the water line, ensuring a continuous supply of filtered water for your home. Engineered for user-friendly installation and replacement, the filter can be set up or swapped out in just a few minutes using the easy twist-on, twist-off mechanism and integrated quick-connect fittings. Changing the cartridge is also a hassle-free process, as the built-in ball and check valve in the filter head eliminates the need to shut off the water supply during cartridge replacement.

In this review, we’ll be reviewing the Culligan US-EZ-4 filter and sharing the need-to-know information about the product. From specifications, pros and cons, and frequently asked questions, we’re sharing our expertise to help you make an informed decision about your next filter purchase.

Product Specs

  • Size: 3.78″ x 8.75″ x 13.75″
  • Capacity: 500 gallons or up to 6 months
  • Filtration Technology: Culligan Filtration Level 4 – Premium Filtration
  • Water Type Filtered: Public tap water. Not for use on microbiologically unsafe or untested well water
  • Contaminants Addressed: Bad taste and odor, aesthetic chlorine taste and odor, sediment, lead, cysts, mercury, turbidity, chloramines
  • Certifications: NSF/ANSI Standards 42, 53, and 401
  • Flow Rate: 0.5 GPM
  • Installation: Potentially requires drilling and installation from a plumber. You should view the installation process to see if it’s something you feel comfortable DIYing.
  • Warranty: 2-year limited warranty


The Culligan US-EZ-4 under-sink filtration system is a reliable and efficient option in the realm of under-sink water filtration. It filters particles up to 0.5 microns and has a flow rate of 0.5 gallons per minute (GPM). While the US-EZ-4 is a step up from water pitcher filters in terms of filtration quality, it lacks the power of more robust reverse osmosis or whole-house filtration systems.


The National Sanitation Foundation (NSF) and the American National Standards Institute (ANSI) have established a set of standards designed to outline fundamental safety criteria for residential water treatment filters, purifiers, and reverse osmosis systems utilized for drinking water.

Here are the relevant certifications the Culligan US-EZ-4 meets:

  • NSF/ANSI 42: Filters meet this certification for their ability to decrease aesthetic impurities, such as chlorine taste and odor. These filters can be categorized as either point-of-use systems installed under the sink or in water pitchers, or point-of-entry systems installed for the entire household.
  • NSF/ANSI Standard 53: This standard is focused on the reduction of health-related contaminants in drinking water and evaluates the capability of water treatment systems to reduce specific contaminants such as lead, volatile organic compounds (VOCs), asbestos, and other potentially harmful substances.
  • NSF/ANSI Standard 401: Standard 401 addresses the reduction of emerging contaminants and incidental contaminants not covered by other standards.

Flow Rate

The flow rate of the Culligan US-EZ-4 is 0.5 gallons per minute (GPM). Generally, a flow rate of 0.5 GPM is considered acceptable for most household tasks like washing hands and doing dishes. If your main concern is the filtration performance and you prioritize water quality over speed, a flow rate of 0.5 GPM may be sufficient. However, if you use a lot of water quickly or have multiple people using water simultaneously, a higher flow rate might be more convenient.


While the US-EZ-4 displays decent filtration capacity and flow rate, it does have some limitations to be aware of. The US-EZ-4 isn’t strong enough to filter out some prominent contaminants. It can filter out most bacteria and parasites like cryptosporidium and giardia, but it may not be fine enough to filter out viruses or dissolved minerals. This system also won’t help with hard water issues. Finally, this system is built to work primarily for cold water, with a temperature maximum of 100 degrees Fahrenheit. The product also needs to be protected from freezing temperatures, as it can cause cracks and leakage.

Installation and Maintenance

The Culligan US-EZ-4 comes with your installation necessities, including the filter head and built-in bracket, mounting screws, and ¼-inch plastic tubing, among other parts. Some users reported needing to purchase additional parts to complete the installation process, so keep that in mind when purchasing. Here’s a brief overview of the installation process, which can be a little complicated and may require a plumber. For more detailed information, you can check out instructions directly from the manufacturer:

  1. Choose the faucet location, ensuring it’s on a flat surface. The faucet can fit through a 9/16-inch hole. If you need to drill a hole, wear personal protective equipment to minimize dust inhalation and irritation. Do not attempt to drill through an all-porcelain sink or a counter that is more than 1″ thick.
  2. Mount the faucet by inserting the spout into the faucet body and tighten the spout nut onto the body. Do not tighten any elements of the sink with pliers, as this could strip the threads on your equipment.
  3. Turn off the cold water supply line and let all water drain from the line.
  4. Install the water supply adapter using Teflon tape, screws, and nuts.
  5. Mount the filter system by using the mounting bracket as a template to mark screw locations, then screw the filter head into the marked spots.
  6. Connect the supply adapter to the inlet of the filter. You’ll need to determine the length of plastic tubing needed to connect the left side of the filter to the supply adapter, then cut the tubing to fit. After cutting the tubing, wet the inside with water and insert it into the supply adapter until the 5/8-inch mark is flush with the fitting.
  7. Connect the faucet. You’ll need to determine the length of plastic tubing needed to connect the right side of the filter to the faucet, then cut the tubing to fit. Next, slide the plastic compress nut over the tubing followed by the ferrule and push the tubing into the end of the faucet stem and tighten. Finally, remove the spare battery from the side of the filter cartridge and put it in the slot just below the Culligan logo.
  8. Install the cartridge by holding the cartridge from the bottom and lining up the arrow on the cartridge with the unlocked padlocked symbol on the filter head, then insert the cartridge and turn the arrow to the locked padlock symbol.
  9. Put the filter into operation by turning on the water supply valve and seeing if there are any leaks. Turn on the faucet and check for leaks. If you have a leak, check the troubleshooting portion of the user manual.

While installation is a bit complex, maintenance on the system is easy and the system features an LED light that will alert you when it’s time for a replacement (which should be every 500 gallons or 6 months). To replace the filter cartridge, just turn off the water supply to the filter, turn the arrow to the unlocked position, and replace the old cartridge with the new cartridge and lock it in place. Flush the system for 10 minutes to remove carbon fines and check for leaks. To replace the battery, simply remove it from the slot below the Culligan logo and replace it with a new one. When inserted correctly, the LED will blink red for 30 seconds and then shut off.

Pros and Cons

Like any system, the Culligan US-EZ-4 has its pros and cons. In this section, we’ll outline the perks and drawbacks of this water filtration system.


  • Great Tasting Water: The water that comes out of the US-EZ-4 is clean, clear, and tastes just like bottled water, according to users.
  • Affordable: Compared to other under-sink filtration systems of similar quality, the EZ-4 is much less expensive than its competitors.
  • LED Indicator: The LED indicator at the base of the faucet makes it easy to know when your filter needs to be changed.


  • May Need Additional Parts: Some users have reported that the ⅛-inch supply line to the filter is non-standard, and they had to purchase additional parts or call a plumber to make the installation work.
  • Difficult Installation: In tangent with the above point, some users found the installation process to be too difficult, requiring a plumber’s assistance.
  • Frequent Replacement: While maintenance requirements on this unit are pretty low, the filter does need to be replaced every 6 months, and the cost can add up considerably over the year.


What is the flow rate of the Culligan US-EZ-4 filter?

The Culligan US-EZ-4 has a flow rate of 0.5 gallons per minute (GPM).

What does the Culligan US-EZ-4 Filter remove?

This under-sink filtration system removes bad taste and odor, aesthetic chlorine taste and odor, sediment, lead, cysts such as giardia and cryptosporidium, mercury, turbidity, particulate class I, VOC’s, MTBE, and chloramines.

Will the Culligan US-EZ-4 filter work with my existing faucet?

The flow rate of these filters may not be suitable for a complete kitchen faucet setup. Culligan suggests using the US-DC line for optimal performance in this specific application.

How long does the Culligan US-EZ-4 filter last?

The US-EZ-4 has a filter life of 500 gallons or 6 months.


The Culligan US-EZ-4 is a reliable choice for enhancing the quality of your household’s drinking water. Its efficient filtration capabilities and LED indicator light make it a practical addition to any kitchen. The dedicated faucet ensures a seamless and compatible supply of filtered water for your home and it comes at a much lower price point than its competitors. It’s worth noting that the flow rate may not be optimal for a full kitchen faucet, and some users reported having trouble with the installation. Keep in mind that if you purchase this unit you may need additional parts or the assistance of a professional to complete the installation process.

As you’re exploring under sink filtration systems, we recommend comparing the US-EZ-4 to other systems in the category. We’ve compiled insights into under-sink filtration systems to help you compare options and make the best choice for your home. While you’re there, check out our top-rated systems like the Aquasana Claryum® 3-Stage – AQ-5300. This under-sink system lasts 100 gallons longer than the US-EZ-4 and reduces 78 contaminants. It’s also equipped with a pre-filter to separate sediment and rust, leading to the reduction of 15x the contaminants of the leading water pitcher. Finally, this system’s dedicated faucet comes in three different color options so you can match your home’s aesthetic.

We hope this review gave you some more information about the Culligan US-EZ-4 water filtration system. For more information, check out other systems we’ve covered to see which option is best for your home!

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