Replacing a water filter cartridge sounds simple — until you realize there are dozens of cartridge styles, sizes, and configurations available. Choosing the wrong replacement can lead to poor filtration performance, leaks, or a cartridge that simply won’t fit your housing.

This guide walks you through the key steps to correctly identify your existing filter cartridge so you can confidently source the right replacement.

Please note that it is always recommended to have water tested to identify the specific filtration needs of your water supply. 

Step 1: Measure Your Cartridge

Before identifying the cartridge style, start with three basic measurements:

• Overall Length
• Outside Diameter (O.D.) 
• Inside Diameter (I.D.)

These measurements help determine the cartridge size and compatibility with your filter housing.

Key Measurements

• Length (L): Overall cartridge height
• Outside Diameter (OD): Width across the outside of the cartridge
• Inside Diameter (ID): Opening size in the center

Step 2: Identify the End Type

Filter cartridges use different end cap configurations. Boshart only carries “A” Open End Type. If your filter does not have an "A" open end type you will not be able to purchase it from Boshart.

Double Open End (DOE)

If both ends are Type “A” open ends, the cartridge is considered a Double Open End (DOE)

Single Open End (SOE)

If the cartridge has:

• One open end
• One specialized end cap

it is considered a Single Open End (SOE)

SOE cartridges are typically manufacturer-specific and may need to be sourced directly from the original manufacturer.

Important Note:
GAC (Granular Activated Carbon) cartridges may appear closed on the bottom even though they are designed for normal operation.

Sealing Design Difference: 

DOE - designed to seal on the top and the bottom by compression against the round knife seat seal in the filter head (top) and in the filter bowl (bottom). These are universal and fit the majority of filter housings on the market.

 

Step 4: Check for a Core

Different cartridge styles use different internal support structures. Spun Poly has no core but all other materials do. These cores are made from one of the below 3 materials: 

• Plastic
• Tin
• Stainless steel

Identifying the core material can help determine the correct replacement, especially in high-temperature or specialty applications.

Step 5: Identify the Cartridge Type

Once you’ve determined the size and end style, the next step is identifying the cartridge type. 

Sediment Cartridges

Sediment cartridges remove dirt, rust, sand, and suspended particles from water.

Available in:

• Standard 2-3/4" diameter
• Giant 4-1/2" diameter
• 10" and 20" nominal lengths

Spun Poly

• 14-SP1
• 14-SP2
• Giant: 14-GSP1, 14-GSP2

Best for:

• Fine sediment removal
• High dirt-holding capacity
• Economical filtration

Pleated Polyester

• 14-PPE1
• 14-PPE2
• Giant: 14-GPPE1, 14-GPPE2

Best for:

• Reusable/washable applications
• Lower pressure drop

String Wound – Poly Core

• 14-SWP1
• 14-SWP2
• Giant: 14-GSWP1, 14-GSWP2

Best for:

• Heavy sediment loads
• Gradual depth filtration

  

High Temperature Cotton

304 Stainless Steel Core (FDA)

• 14-SWBC1
• 14-SWBC2
• Giant: 14-GSWBC1, 14-GSWBC2

Tin Core (NON-FDA)

• 14-SWNC1
• 14-SWNC2

Best for:

• Higher temperature applications
• Specialty industrial systems

Activated carbon cartridges reduce:

• Chlorine
• Taste
• Odor
• Organic contaminants

Carbon Block

Excellent for:

• Chlorine reduction
• Fine filtration

Cyst Removal Carbon

Designed for:

• Enhanced contaminant reduction
• Cyst protection applications

GAC (Granular Activated Carbon)

Ideal for:

• Taste and odor reduction
• General carbon filtration

Carbon Wrap

Available in standard and Giant sizes

Important:
Carbon Wrap cartridges should only be used with chlorinated water supplies.

In-Line Icemaker / Dispenser 

Commonly used for:

• Refrigerators
• Beverage dispensers
• Icemakers

Step 6: Determine the Micron Rating

The micron rating indicates how fine a particle the cartridge can filter. Unfortunately, this can sometimes be difficult to identify on older or unlabeled cartridges. In many cases, the best approach is to select a micron rating appropriate for the application rather than trying to exactly match the previous cartridge.

General Guidelines

Micron Rating	Typical Use
50–100 Micron	Coarse sediment
20–30 Micron	General sediment filtration
5–10 Micron	Fine sediment
1 Micron or lower	Fine filtration / specialty applications

Note a 50 micron rated filter will allow larger particles to pass through than a 5 micron rated filter. Common micron ratings for filters are 100, 75, 50, 25, 10, 5, 1 and 0.5.

Final Tip: Make Future Replacements Easier

Once you identify the correct cartridge:

✅ Keep the label
✅ Tape it near the housing
✅ Record the cartridge part number

This can save significant time during future maintenance.

Still Unsure?

If you’re unable to identify your cartridge, take clear photos of:

• The housing (showing make/model)
• The cartridge beside a tape measure

Send the photos to us and our team will be better equipped to verify exactly what you have and recommend the correct replacement cartridge.

Have further questions about this subject?

Head over to Boshart's Knowledge Base: technical product information, guidelines, and more.