Frigidaire sells two refrigerator water filters that cross-reference lists often mix up. Water Filters FAST stocks both the WF3CB and the ULTRAWF.

Neither one fits the other's refrigerator. Frigidaire built them for different filter systems, and the housing inside the fresh food compartment accepts one shape.

The cap on the old cartridge settles the question in about four seconds. Pull it, read it, and order the number printed there.

Written by the Water Filters FAST filter experts. Reviewed by Phil McNamara, owner, Water Filters FAST. Updated August 2026.

Read the cap first

Frigidaire prints the part number on the cap end of the cartridge. That is the end that stays visible after installation, and it outlasts the printed wrap around the body.

Open the fresh food compartment and find the filter. Turn the cartridge and pull it out. Hold the cap under a light and read the raised characters.

A cap reading WF3CB takes the Frigidaire WF3CB PureSource3 filter. A cap reading ULTRAWF takes the Frigidaire ULTRAWF PureSource Ultra filter.

Nothing else in the refrigerator answers the question this quickly. The model sticker gives an answer eventually, and the cap gives it now.

When the cap has worn smooth

Ink wears off a cap that has spent six months in a wet housing. One check works without it.

Look for an air filter. Frigidaire pairs the PureSource Ultra water system with the PAULTRA PureAir Ultra air filter, and the Water Filters FAST listing for that air cartridge states plainly that it fits the same refrigerators as the ULTRAWF.

A refrigerator carrying a PAULTRA air filter is a PureSource Ultra refrigerator. Its water filter is the ULTRAWF.

The shape of the housing is the other clue. Frigidaire mounts the WF3CB as a slide-in cylinder inside a PureSource 3 housing on the top right side of the inner compartment. A cartridge that slides straight into a housing in that position is a WF3CB.

What the WF3CB does

The WF3CB is Frigidaire's genuine PureSource 3 cartridge. Frigidaire built it for refrigerators running the PureSource 3 filter system, and it cleans the water going to the dispenser along with the water that makes the ice.

Frigidaire rates it at about 200 gallons or six months. It flows a half gallon per minute, works between 30 and 100 PSIG, and handles water from 33 to 100 degrees Fahrenheit.

NSF and ANSI certified the WF3CB under Standards 42 and 53. The media reduces chlorine taste and odor, class I particulates, lead, cysts, turbidity, mercury, and a list of herbicides and pesticides including atrazine, 2,4-D, toxaphene, lindane, and alachlor.

Certain Electrolux refrigerators run the PureSource 3 system as well. Those models take the WF3CB with no adapter.

What the ULTRAWF does

The ULTRAWF is Frigidaire's PureSource Ultra cartridge. It fits every PureSource Ultra refrigerator model Frigidaire has built.

Its contaminant list runs longer than the WF3CB list. On top of chlorine, lead, cysts, and turbidity, the ULTRAWF reduces asbestos, benzene, ethylbenzene, styrene, tetrachloroethylene, TTHM, carbofuran, and a set of chlorinated solvents.

Frigidaire conforms the ULTRAWF to NSF/ANSI 53 for volatile organic chemical reduction. Testing against the VOC surrogate returned an average reduction of 99.8 percent.

The two filters side by side

Frigidaire prints a 200 gallon and six month rating on the WF3CB. The ULTRAWF listing carries no life figure, and the owner manual for that refrigerator gives its interval.

A household drawing heavily on the dispenser reaches a gallon limit sooner than the calendar.

Multi-packs of both filters

Water Filters FAST sells each cartridge as a single, a 2 Pack, a 3 Pack and a 6 Pack. A 2 Pack covers two change intervals.

Where cross-reference numbers go wrong

Aftermarket sellers publish long cross-reference lists, and those lists blur these two Frigidaire numbers together more often than any other pair in the catalog.

The overlap is easy to understand. Both cartridges carry Frigidaire branding and both live in the top of the fresh food compartment. A list built by matching brand and position puts them in the same row.

The housing decides, and no cross-reference list can see your housing. Read the cap on the cartridge you removed and trust that number over any list.

Order the wrong one and the fit tells you immediately. A WF3CB will not seat in a PureSource Ultra housing.

The rest of the Frigidaire line

Frigidaire runs five refrigerator water filter families, and Water Filters FAST stocks all of them.

The Frigidaire EPTWFU01 is the number newer Frigidaire refrigerators carry. An owner shopping a recent model who finds neither WF3CB nor ULTRAWF on the cap should check that number next.

The names track the build year loosely. PureSourcePlus came first, PureSource2 and PureSource3 followed, and PureSource Ultra arrived alongside the PAULTRA air filter. A refrigerator bought in the last decade sits at the bottom of that table more often than the top.

Age gives you a hint and the cap gives you the answer. Use the hint to narrow the search when a cartridge has already gone out with the trash.

Browse the full Frigidaire refrigerator water filter collection for every cartridge in the range.

Signs a Frigidaire filter is finished

Flow drops first. A dispenser that filled a glass in ten seconds starts taking twenty, and the ice maker stops keeping up with a weekend of company.

Taste follows. Chlorine comes back to the water and to the ice, and cubes that used to come out clear start coming out cloudy.

The indicator light is the third signal. Frigidaire counts water through the dispenser, and a household that runs mostly on ice can pass the rating before the light turns.

Noise sometimes arrives with the rest. A loaded cartridge makes the dispenser valve work harder, and the refrigerator groans on the first second of every pour.

Change on six months and treat every other signal as confirmation. Write the install date on the cap with a marker before it goes in.

Changing either cartridge

Both filters change without tools. Frigidaire designed each one for a quarter turn.

Turn the old cartridge counterclockwise until it releases and pull it straight out. Hold a cloth underneath for the water still sitting in the housing.

Push the new cartridge in and turn it clockwise until it stops. Watch the housing for thirty seconds afterward.

Run three gallons through the dispenser before drinking. Fresh carbon sheds a fine dust on the first draw, and grey water at the start clears on its own.

Reset the filter indicator last. On most models a three second hold on the dispenser panel reset button changes the light back.

Ordering and returns

Returns run 30 days and a satisfaction guarantee covers every cartridge.

Call 855-789-FAST with the model number off the sticker inside the fresh food compartment when the cap gives nothing back. The filter experts will match it against the catalog.

Frequently asked questions

Can the ULTRAWF replace a WF3CB?

No. Frigidaire built them for different filter systems. A WF3CB seats in a PureSource 3 housing and an ULTRAWF seats in a PureSource Ultra housing.

How does an owner tell which Frigidaire filter a refrigerator takes?

Pull the cartridge and read the number molded into the cap. A refrigerator that also uses a PAULTRA air filter is a PureSource Ultra model and takes the ULTRAWF.

What does the ULTRAWF reduce that the WF3CB does not?

Its media reduces a longer contaminant list, including asbestos, benzene, TTHM, and a set of volatile organic chemicals at a 99.8 percent surrogate average reduction.

How often does a Frigidaire water filter need changing?

Frigidaire rates the WF3CB at 200 gallons or six months. The ULTRAWF listing prints no interval, and the owner manual for the refrigerator gives it.

Does the WF3CB fit an Electrolux refrigerator?

Certain Electrolux models run the PureSource 3 system and take the WF3CB. Read the cap on the old cartridge to confirm.

What is the PAULTRA air filter?

The PAULTRA is Frigidaire's PureAir Ultra air filter. Frigidaire rates it for six months and fits it to the same refrigerators as the ULTRAWF.

A third Frigidaire housing takes a flat block. The PureSource2 WF2CB guide separates it from the WF3CB cylinder in five seconds.

Order the cartridge your cap names

WF3CB or ULTRAWF, and the cap in your hand decides. Call 855-789-FAST or email support@waterfiltersfast.com when the characters have worn away.