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Osmio 4.5 x 20 Inch Carbon Block 5 Micron

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Osmio® Whole House Filter Replacement

Osmio 4.5 x 20 Inch Carbon Block 5 Micron

Replacement 5 micron carbon block cartridge for compatible whole house systems, including the Osmio PRO III XL.

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Osmio 4.5 x 20 Inch Carbon Block 5 Micron replacement filter cartridge

5 Micron Carbon Block Replacement Filter for Whole House Filtration

  • Compatible Cartridge:

    Designed for compatible 4.5 x 20 inch whole house filter housings.

  • PRO III XL Replacement:

    Used as one of the main filter stages within the Osmio PRO III XL Whole House Water Filter System.

  • 5 Micron Filtration:

    Helps capture fine particles before water continues through the rest of the system.

  • Carbon Block Performance:

    Supports chlorine, taste and odour reduction for everyday household water use.
Need the full system? View the Osmio PRO III XL Whole House Water Filter System or browse Osmio Water Filters.

What Does the Carbon Block Filter Do?

The Osmio 4.5 x 20 Inch Carbon Block 5 Micron cartridge is designed to help improve water quality across the home by combining fine particle filtration with activated carbon treatment.

The 5 micron rating means the cartridge can help reduce small particles from the incoming water supply, while the carbon block supports chlorine, taste and odour reduction. This makes it an important stage in the Osmio PRO III XL whole house filtration system.

Buy with Confidence

Your Osmio replacement filter is supplied brand new and backed by the manufacturer’s warranty, with expert support from Regal Flow if you need help choosing or replacing your filter.

Why Carbon Block Filtration Matters

Fine Particle Reduction

The 5 micron rating helps capture fine sediment and small suspended particles from the water supply.

Taste and Odour Support

Activated carbon helps reduce chlorine related taste and odour in household water.

Whole House Use

Designed for point of entry filtration, helping treat water before it reaches taps, showers and appliances.

Important Service Filter

This cartridge is usually replaced more often than the long life Active Ceramics stage.

Why a Carbon Block Instead of Loose Carbon?

Unlike loose granular activated carbon, a carbon block is manufactured as a compressed block of activated carbon. This allows water to pass through a more consistent filter structure, helping provide finer filtration while supporting chlorine, taste and odour reduction. The 5 micron rating also helps capture smaller particles before water continues through the rest of the system.

Is This the Correct Filter for Your System?

  • Correct For:

    Osmio PRO III XL Whole House Water Filter System carbon block replacement stage.

  • Also Suitable For:

    Compatible standard 4.5 x 20 inch whole house filter housings where a 5 micron carbon block cartridge is specified.

  • Not Suitable For:

    Small under sink filters, countertop systems, reverse osmosis systems or non standard housings.

  • Check Before Ordering:

    Confirm the cartridge size, housing size and filter stage before purchasing.

Why Buy from Regal Flow?

Fast, Free UK DeliveryQuick dispatch with no hidden delivery charges.
Expert Product AdviceSpeak to a real water treatment specialist.
Manufacturer WarrantyCovered against manufacturing defects.
Independent RetailerHonest advice across multiple leading brands.

Why This Filter Matters in the PRO III XL System

The Osmio PRO III XL uses multiple cartridges because each filter has a different job. The Carbon Block 5 Micron cartridge is one of the key service filters because it helps reduce fine particles while supporting taste, odour and chlorine reduction.

As water passes through a whole house system, the carbon block helps polish the water before it continues through the remaining filtration stages. Replacing it at the right time helps maintain water quality and system performance.

Osmio 4.5 x 20 Inch Carbon Block 5 Micron whole house replacement filter

Complete Your Filter Replacement

Active Ceramics Filter

Long life filtration stage. Typically replaced every 2 to 3 years.

View Product
KDF and GAC Filter

Supports chlorine, taste and odour reduction while helping protect downstream filtration media. Typically replaced every 12 to 18 months.

View Product
Carbon Block 5 Micron

Fine filtration and activated carbon polishing. Typically replaced every 6 to 12 months.

Current product

Replacement Schedule Advice

Every filter within the Osmio PRO III XL has a different role and replacement interval. Replacing each cartridge at the right time helps maintain water quality and system performance.

Every filter within the Osmio PRO III XL has a different role and replacement interval. Replacing each cartridge at the recommended time helps maintain water quality and keeps your whole house filtration system performing as intended.

Why This Cartridge Needs Replacing More Often

The Carbon Block 5 Micron cartridge deals with fine particles and carbon filtration across the whole home, so it works hard during everyday use. Over time, captured particles and used carbon capacity can reduce performance. If water taste, odour or flow changes, this cartridge is one of the first stages to check.

Replacement and Maintenance Guidance

  • Turn Off the Water Supply:

    Always isolate the water supply before opening a whole house filter housing.

  • Release Pressure First:

    Depressurise the housing before unscrewing the sump to reduce the risk of water release.

  • Check the Seal:

    Inspect the housing O ring before refitting the sump. A poor seal can cause leaks.

  • Flush After Replacement:

    Run water through the system after fitting the new cartridge to clear loose carbon fines and settle the filter.

Practical Advice

If the water flow has dropped, this cartridge may be becoming restricted. If taste, odour or chlorine smell has returned, the carbon capacity may be exhausted. If unsure, contact Regal Flow before ordering.

What Comes With This Product?

  • 1 x Osmio Carbon Block 5 Micron Filter:

    4.5 x 20 inch replacement cartridge.

  • Filter Housing Not Included:

    This is a cartridge only, not a complete whole house filtration system.

  • Compatible System Sold Separately:

    The Osmio PRO III XL whole house system is available separately from Regal Flow.

Osmio 4.5 x 20 Inch Carbon Block 5 Micron Specifications

Product Type Whole house replacement filter cartridge
Brand Osmio
Filter Media Activated carbon block
Micron Rating 5 micron
Size 4.5 x 20 inch
Compatible System Osmio PRO III XL Whole House Water Filter System
Compatible Housing Compatible standard 4.5 x 20 inch whole house filter housings
Main Use Fine particle filtration, chlorine, taste and odour support
Typical Replacement Interval 6 to 12 months depending on water quality and usage
Housing Included No
Standalone System No, replacement cartridge only
Manufacturer Warranty Manufacturer warranty against manufacturing defects
Browse the Osmio Collection, shop Replacement Filters, or view the Osmio PRO III XL system.

Downloads and Resources

Osmio PRO III XL compatible system information Compatible System Information

This replacement cartridge is designed for the Osmio PRO III XL Whole House Water Filter System.

View Compatible System
Osmio replacement filter resources Osmio Replacement Filter Support

Browse Osmio systems and replacement filters to help maintain your whole house setup.

View Osmio Collection

Frequently Asked Questions

Does this fit the Osmio PRO III XL?

Yes. This cartridge is designed for use as part of the Osmio PRO III XL Whole House Water Filter System.

Is this the same as the KDF and GAC filter?

No. This is the 5 micron carbon block cartridge. The KDF and GAC cartridge is a separate filter stage.

Is this the same as the Active Ceramics filter?

No. The Active Ceramics filter is a separate long life stage within the Osmio PRO III XL system.

How often should this carbon block filter be replaced?

It is typically replaced every 6 to 12 months depending on household usage and incoming water quality.

What does 5 micron mean?

5 micron refers to the filter rating. It means the cartridge is designed to help capture fine particles from the water supply.

Is the filter housing included?

No. This product is the replacement cartridge only. The housing or complete whole house filter system is sold separately.

Explore More from Regal Flow

Osmio Water Filters and Reverse Osmosis Purifiers

Browse Osmio whole house systems, drinking water filters and replacement cartridges.

View Osmio Collection
Osmio PRO III XL Whole House System

View the complete whole house system that this cartridge is designed to work with.

View Compatible System

Need Help Confirming the Correct Osmio Filter?

If you are not sure whether this is the correct cartridge for your Osmio PRO III XL system, contact Regal Flow before ordering. We can help you check the filter stage, housing size and replacement schedule.

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Replacement Filter Support

Unsure which Osmio cartridge needs replacing? Our support team is available 7 days a week to help you choose the correct filter before you order.

Contact Support Team
Email Support: info@regalflow.co.uk
Telephone Direct: 0121 630 1130

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