Review: Culligan Easy-Change US-EZ-1, US-EZ-3 & US-EZ-4 Under Sink Water Filters

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As part of the Easy-Change (EZ-Change) series, Culligan offers 3 under sink drinking water filtration systems:

  • The US-EZ-1 which is the most affordable and for basic filtration only
  • The US-EZ-3 for advanced filtration needs
  • And lastly, for premium filtration and thus the most expensive, the US-EZ-4
Culligan Easy-Change US-EZ-1

Culligan US-EZ-1

Flow Rate:0.5 gpm
Filter Capacity:3,000 gal
NSF Certifications:42
Warranty:2 Years

Our Rating

Culligan Easy-Change US-EZ-3

Culligan US-EZ-3

Flow Rate:0.5 gpm
Filter Capacity:500 gal
NSF Certifications:42, 53
Warranty:2 Years

Our Rating

Culligan Easy-Change US-EZ-4

Culligan US-EZ-4

Flow Rate:0.5 gpm
Filter Capacity:500 gal
NSF Certifications:42, 53, 401
Warranty:2 Years

Our Rating

Culligan Easy-Change Series – Key Features

All three filter models feature a single carbon-based filter stage and are rated at .5 gallons per minute service flow rate which is okay for drinking and cooking needs. Required water pressure: 30 to 100 psi.

Being the most elementary, the EZ-1 is NSF Standard 42 certified to reduce chlorine and particulates class III. In other words: If all you care about is improved water aesthetics – think taste and smell – this filter is absolutely sufficient.

Each cartridge has a maximum filtering capacity of 3,000 gallons or up to 12 months.

FYI: Particulates class III have a size between 5µm to 15µm.

If apart from chlorine and particulates class I (0.5µm to 1µm) you also want to get rid of cysts (99.9%), turbidity (98.5%), lead (about 99.0%), atrazine (94.1%) and lindane (98.2%), you should opt for the EZ-3.

*All reduction rates are according to NSF Standard 53.

Its capacity is 500 gallons or a maximum of 6 months, whichever comes first. Obviously, this is less than what you get with the EZ-1, but no reason to worry about high maintenance demands. This won’t be the case.

For even higher filtration requirements the EZ-4 is your best bet. In addition to all the impurities listed above, it’ll also take care of chloramines, MTBE, mercury, chloroform, dozens of VOCs, perfluorinated chemicals (PFOA & PFOS) and so-called emerging contaminants for increased water safety.

Emerging contaminants include stuff like Phenytoin, Ibuprofen, Naproxen, Estrone, Bisphenol A and Nonyl Phenol.

This has earned the unit 4 independent NSF certifications:

  • Standard 42
  • Standard 53
  • Standard 401
  • And Protocol P473

The last two are pretty hard to find which underlines the sophistication of the filtration process.

Capacity: 500 gallons or 6 months.

Information overload? Check out this table:

(Mobile Hint: Swipe to Scroll)

Bad tastes and odorsYesYesYes
Particulates99.9% (class III)99.9% (class I)99.9% (class I)
LeadAbout 99.0%99.3%
Emerging contaminants (e.g. Ibuprofen, Phenytoin)>95.4%
PFOA + PFOS>95.8%

EZ-1, EZ-3 & EZ-4 Pros

There are three things that we like about the Culligan US-EZ series in particular and that is, firstly, the compatible head assembly which fits all replacement cartridges (EZ-1, EZ-3 & EZ-4). So if all of a sudden you want water of higher purity you can easily upgrade your basic or advanced filter.

Secondly, the head features a simple twist on/off mechanism designed for convenience. This avoids the mess that comes with changing out traditional filters. Instead, they can be replaced within seconds and without turning off the feed water supply – no need for buckets, towels or wrenches.

Thirdly, each product is backed by a 2-year limited manufacturer warranty.

Culligan EZ-1

The Culligan EZ-1 – learn more on

Culligan EZ-3

The Culligan EZ-3 – learn more on

Culligan EZ-4

The Culligan EZ-4 – learn more on


The good news is that Culligan Easy-Change under sink systems come with everything you need for setup and operation.

What’s more, quick connect fittings and detailed DIY instructions make the installation somewhat easier. So if you are a practiced do-it-yourselfer there’s probably no need for calling a plumbing professional.

The bad news is that if your kitchen sink or countertop does not have a pre-drilled hole (e.g. used for soap dispenser or water sprayer) you’ll have to drill one for the dedicated chrome faucet that is part of the system.

Without going into full detail, here are some step-by-step instructions:

  1. Start by selecting a location for your faucet if you are not planning on using a pre-drilled hole. The included faucet fits any 9/16″ hole. Most pre-drilled holes are 13⁄8″ or 11⁄2″.
  2. First drill a pilot hole using a 1/4″ drill bit. Then use a 9/16″ or 5/8″ drill bit to drill a hole completely through sink/countertop.
  3. Insert spout into faucet body and tighten using spout nut. Attach black rubber gasket onto threaded faucet stem.
  4. Insert faucet through hole and tighten from underneath using metal washer and white plastic stem nut. Hand-tighten only.
  5. Next turn off the cold water supply and drain all remaining water by opening the kitchen faucet.
  6. Install the feed water adapter. Use Teflon tape on threaded ends.
  7. Connect cold water line to existing faucet. Hand-tighten first, then snug nut with wrench.
  8. It’s time to mount the filter unit under your sink. Allow 1½” clearance below filter for cartridge replacements. Mount vertically.
  9. Connect the feed water adapter to the inlet port of the unit. Make sure to allow enough tubing to prevent kinking. Pro tip: Place a mark 5/8″ from both ends of the tubing. Push tubing into push fittings until mark is flush.
  10. Connect the filtered water faucet in the same manner. For the faucet connection, slide plastic compression nut over tubing followed by ferrule before placing insert into the end of tubing. Push tubing firmly into the end of the faucet stem. Hand-tighten compression nut. Then tighten another ½ turn using a wrench.
  11. Add battery into slot at faucet (not for EZ-1).
  12. Lastly, install the filter cartridge. Simply insert and turn arrow to locked padlock symbol.
  13. Turn on water supply. Check for leaks. Open drinking water faucet and flush unit for 10 minutes.


Prefer video?

The Package (Parts)

  • Filter head with built-in bracket
  • Filter cartridge
  • Mounting screws
  • Water supply adapter
  • Lead-free chrome faucet with fittings
  • Lithium battery (US-EZ-3/4 only)
  • 1⁄4″ plastic tubing
  • Cartridge change reminder sticker


The modular filter design allows for quick and easy filter changes and avoids the mess that traditional cartridges often make: Simply twist and pull down to remove old. Push up and twist to install new.

How often do you have to change filters?

Like we said, the US-EZ-1 lasts for up to 3,000 gallons or 12 months, US-EZ-3 and US-EZ-4 for up to 500 gallons or 6 months. The built-in LED filter life indicator will let you know when it’s time for a replacement (EZ-3 & 4 only).

All in all, the annual maintenance costs seem reasonable.


Looking for a manual? You can find one here.

EZ-1, EZ-3 & EZ-4 Cons

You are right, half a gallon water flow per minute at 60 psi does feel a little slow.

Also, the “chrome” faucet that’s included in the package is made from cheap plastic except for its metal spout. We would have appreciated an all-metal faucet.

Besides, a 1/2″ feed water adapter is part of the deal. However, if your home uses 3/8″ supply lines it won’t fit, so you will have to visit the local hardware store.

Furthermore, some customers reportedly had issues with leaks. One reason for this are the plastic connectors. You should seriously consider replacing them with brass. If on the other hand water leaks due to a cracked housing there’s really not much you can do.

Culligan Easy-Change Series Review: Our Verdict + Best for

The Culligan Easy-Change Series is best for people who want an under sink drinking water filtration system that’s simple to install, low in maintenance, and most importantly provides clean and great-tasting water – also a perfect solution for people on a tight budget.

Most customers are very happy with their purchase. Our verdict: 4 stars for the Easy-Change 4, 3.5 for the EZ-3 and 3 stars for the EZ-1.

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This completes our review of the Culligan Easy-Change series. If you have any questions, please don’t hesitate to leave a comment below!

About the Author Gene Fitzgerald

Gene Fitzgerald has been with BOS since the very beginning. She is head of content creation and has fully immersed herself into the home water treatment industry only to become an expert herself. Outside of BOS, Gene loves reading books on philosophy & social issues, making music, and hiking.
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