THE COMPLETE REPLACEMENT GUIDE
Choosing the Right Water Filter in South Africa
A practical guide to sediment, carbon, reverse osmosis, Big Blue, fridge, coffee-machine and specialist replacement filters.
Replacing a water filter sounds simple until you start looking at the available options. Should you use sediment or carbon? What is GAC? What does an RO membrane do? Is a 10-inch cartridge interchangeable with Big Blue?
The correct filter depends on two things: what you are trying to remove from the water, and which filtration system you already have.
This guide explains the common filter types available in South Africa, how multi-stage systems work and what to check before ordering a replacement.
Identify the stageSediment, carbon and membranes do different jobs
Match the formatDimensions, connections and flow must agree
Confirm compatibilityUse the system model or existing part number
THE BASICS
What Is a Water Filter?
A water filter is a component designed to reduce specific substances or particles as water passes through filtration media. Different filter types perform different jobs.
Sediment
Captures suspended dirt, rust and particles.
Activated carbon
Improves taste and odour and reduces certain chlorine-related compounds.
RO membrane
Uses membrane separation to reduce dissolved substances.
“Water filter” therefore does not describe one universal product. A system may contain one cartridge or several stages working together.
Frost supplies filters across many formats. The current range covers reverse osmosis, Big Blue housings, purifier/mineraliser units, fridges, coffee machines, drinking-water fountains and commercial filtration.
MULTI-STAGE FILTRATION
How Does a Water Filtration System Work?
Modern purification systems often use several stages. Instead of asking one cartridge to perform every task, each stage addresses a different part of the treatment process.
The exact order and filter types depend on the system. Frost's current RO range includes sediment, GAC, carbon block, RO membrane and taste-and-odour cartridges.
FIRST-STAGE PROTECTION
Sediment Filters: What Do They Remove?
A sediment filter is generally the first stage. It mechanically captures sand, silt, rust, dirt, pipe debris and other suspended solids, protecting later carbon cartridges and RO membranes from unnecessary loading.
Polypropylene
An economical disposable first stage, well suited to capturing suspended particles before later filtration.
Large surface area
The folded filter surface can provide higher dirt-holding capacity or useful flow characteristics.
Progressive depth
Tightly wound material traps particles through progressively finer spaces.
Which type is appropriate depends on the housing, flow requirement and water conditions. Frost's 20-inch polypropylene Big Blue sediment cartridge is listed at 60 litres per minute.
Browse Frost Big Blue filters →ADSORPTION
What Is an Activated Carbon Water Filter?
Activated carbon is widely used in drinking-water filtration. Compounds adhere to its large internal surface area as water flows through the media. It is commonly used for chlorine taste, unpleasant odours, certain organic compounds and general taste quality.
GAC
Granular Activated Carbon uses loose granules. It provides strong adsorption with relatively free flow and is common in multi-stage and RO systems.
Carbon block
Compressed activated carbon forms a porous solid block, combining adsorption with a degree of particulate filtration depending on design and micron rating.
Neither automatically. The correct replacement should match the system's original specification, cartridge dimensions and intended flow.
MEMBRANE TREATMENT
What Is a Reverse Osmosis Filter?
Reverse osmosis—usually abbreviated RO—is a more advanced water-treatment process. Water is pushed under pressure through a specialised semi-permeable membrane, allowing water molecules through while reducing many dissolved substances.
The membrane is the defining RO stage. Conventional sediment and carbon filters normally protect it before the water reaches the membrane.
Frost's current RO replacement range includes PP sediment, GAC, carbon block, nano silver antibacterial carbon, a reverse-osmosis membrane and a taste-and-odour finishing filter. Each has a different job and service life; replacing only the membrane does not mean the whole system has been serviced.
Filter life is affected by water quality, consumption, sediment, chlorine, pressure and frequency of use. Follow the recommendation for the specific system and cartridge.
View the Frost 100 GPD RO membrane →HIGHER-CAPACITY FORMAT
What Are Big Blue Water Filters?
Big Blue refers to a larger housing and cartridge format commonly used where greater flow or filtration capacity is needed, including residential, commercial and whole-house applications.
Slimline RO cartridge
Point-of-use drinking-water systems
Big Blue cartridge
Higher-flow and higher-capacity applications
Frost's 20-inch range includes standard sediment, string-wound sediment, pleated sediment, carbon block, GAC and Carbon Block Nano options. A Big Blue system can make sense for higher flow, heavier sediment, treatment before multiple outlets or commercial use.
Shop Big Blue replacement filters →DISPENSER FILTER BOTTLES
Purifier & Mineraliser Filters
Some Frost dispensers use a purifier and mineraliser bottle rather than a pre-filled 18.9L bottle or direct mains connection. These systems use dedicated replacement components: a carbon filter, ceramic dome, mineral stones or a complete combo set.
Ceramic dome
Provides fine physical filtration through ceramic pores. Frost specifies particles from approximately 0.3 micron and larger, with a guideline around 12 months depending on water quality.
Carbon stage
Addresses chlorine, unpleasant tastes and odours and certain organic chemicals as specified for the PM combination system.
Mineral stones
Form part of the final mineralisation configuration after the other filtration media.
Choose parts specifically for the PM system. Generic RO or Big Blue cartridges are not substitutes merely because they are also called water filters.
Browse Frost PM replacement filters →APPLIANCE FILTERS
Fridge Water Filters
Fridge filters are designed for refrigerators that dispense chilled water or make ice. Modern appliances often use proprietary internal cartridges. Identify the refrigerator brand and model, current filter part number, cartridge shape and connection type.
Match the part number—not only the brand. A manufacturer may use several incompatible cartridges. For example, Samsung uses multiple DA29 formats and LG uses LT600P, LT700P, LT800P and LT1000P compatible formats.
Internal vs external fridge filters
Some fridges use an external inline filter behind the appliance rather than a proprietary internal cartridge. For an external filter, check connection diameter, flow direction, physical size, operating pressure and filtration specification.
Browse Frost fridge water filters →APPLIANCE FILTERS
Coffee Machine Water Filters
Automatic coffee machines often use cartridges inside the water reservoir. They can help manage mineral accumulation, support consistent water quality and influence brewing taste. Compatibility matters because manufacturers use different shapes and connections.
A filter does not necessarily eliminate descaling or maintenance. Always follow the coffee-machine manufacturer's servicing programme.
Browse Frost coffee machine filters →HIGH-USE EQUIPMENT
Water Fountain & Commercial Chiller Filters
Commercial drinking-water equipment can use conventional sediment and carbon cartridges. Frost has dedicated filter categories for stainless-steel drinking-water fountains and commercial straight chillers. Because many people may draw water throughout the day, maintaining these stages is particularly important.
Fountain filters
Replacement stages for Frost stainless-steel drinking-water fountains.
Browse filters →Straight chiller filters
Filtration cartridges for higher-use commercial chilling equipment.
Browse filters →START WITH THE PROBLEM
Which Filter Does What?
Chlorine, taste & odour
Activated carbon—either GAC or carbon block—is commonly used. The housing size must still match.
Suspended sediment
Use melt-blown, pleated or string-wound sediment filtration according to the system and water conditions.
Final taste polishing
A dedicated post-carbon or taste-and-odour cartridge is often the last RO stage.
Dissolved salts
Use reverse-osmosis membrane separation. Conventional sediment and carbon are not designed primarily for this job.
Carbon and RO are often combined rather than treated as alternatives: carbon works through adsorption, while RO uses membrane separation.
SERVICE LIFE
How Often Should a Water Filter Be Changed?
There is no universal “every six months” rule. Filter life depends on cartridge type and size, water volume, incoming quality, sediment, chlorine, pressure and manufacturer specifications. A home using 10 litres a day and a commercial kitchen using hundreds of litres load the same filter very differently.
A loaded sediment or carbon cartridge can become restrictive.
This may indicate exhausted carbon or another problem with the water or system.
Unexpected particles or discolouration should be investigated.
Do not use a cartridge indefinitely simply because the water looks clear.
Declining membrane performance may mean the membrane or other stages need service.
Do not replace random cartridges when unsure. Have the system inspected and identify every stage first.
Can you clean and reuse a filter?
Most sediment, carbon and RO drinking-water cartridges are disposable. Washing a carbon block does not restore adsorption capacity. Only clean a cartridge when its manufacturer explicitly identifies it as reusable.
PARTICLE SIZE
What Does Micron Rating Mean?
A micron rating describes the approximate particle size the filtration medium is designed to capture. One micron is one-thousandth of a millimetre.
Smaller is not automatically better. A very fine cartridge in dirty water can clog quickly, restrict flow and create pressure drop. A coarser first stage can protect a finer second stage, so selection should consider the whole system.
COMPATIBILITY FIRST
How Do You Choose the Correct Replacement?
Identify the systemRO, Big Blue, under-counter, PM dispenser, fridge, coffee machine or commercial equipment?
Confirm cartridge size10-inch slimline, 20-inch Big Blue or a proprietary appliance shape?
Identify the stageSediment, carbon and membranes are not interchangeable.
Read the existing cartridgeFind the product number, micron rating, dimensions and filter type.
Verify compatibilityEspecially important for refrigerator and coffee-machine cartridges.
AT-A-GLANCE REFERENCE
Quick Water Filter Comparison
| Filter type | Primary purpose | Typical application |
|---|---|---|
| Sediment | Suspended particles | Pre-filtration |
| Pleated sediment | Particle filtration | Higher dirt capacity / flow |
| String wound | Sediment filtration | Pre-filtration |
| GAC carbon | Taste, odour, chlorine | Drinking water / RO |
| Carbon block | Adsorption + filtration | Drinking water / RO |
| RO membrane | Dissolved-solids reduction | Reverse osmosis |
| Post carbon | Final taste polishing | RO systems |
| Ceramic | Fine physical filtration | PM purifier systems |
| Big Blue | Higher-capacity format | Whole-house / commercial |
| Fridge filter | Appliance-specific filtration | Refrigerators |
| Coffee filter | Water / scale management | Coffee machines |
BEFORE YOU ORDER
Water Filter Buying Checklist
System or appliance modelIdentify exactly what uses the cartridge.
Existing part numberThe strongest clue for proprietary filters.
Cartridge dimensionsConfirm length, diameter and physical format.
Filter typeSediment, carbon, membrane or specialist.
Micron ratingMatch it where the system specifies one.
Connection typeCritical for inline appliance filters.
Required flow rateDo not undersize higher-demand systems.
Confirmed compatibilityPhysical fit alone does not prove function.
Replacement intervalPlan maintenance before the new filter expires.
Other stages dueMulti-stage systems may need grouped servicing.
A filter that physically fits but performs a different function is not the correct replacement.
COMMON QUESTIONS
Frequently Asked Questions
How do I know which water filter I need?
Start with the system or appliance model and the existing filter part number. Then match dimensions, connection and filter type. Compatibility is especially important for fridge and coffee filters.
What is the difference between sediment and carbon?
Sediment filters capture suspended particles. Activated carbon uses adsorption to address chlorine and certain compounds affecting taste and odour.
What is the difference between GAC and carbon block?
GAC uses loose granular activated carbon. Carbon block compresses activated carbon into a porous solid. They have different flow and filtration characteristics.
Does a carbon filter remove sediment?
It may capture some particles—particularly carbon block—but a dedicated sediment cartridge should normally handle suspended solids.
What is the best water filter for drinking water?
There is no universal best. The appropriate system depends on incoming water and what you need to reduce. Carbon may be sufficient for some; others need multi-stage or RO treatment.
How often should I replace a water filter?
Follow the manufacturer’s interval for that cartridge. Heavy use and challenging incoming water can shorten service life.
Can I replace only one stage?
Yes, stages can have different service lives. Similar pre-filters are sometimes serviced together; follow the system schedule.
How long does an RO membrane last?
It varies with feed water and maintenance. Frost currently lists approximately 3–5 years for its 100 GPD membrane depending on local water quality.
What is a Big Blue filter?
It is a large cartridge format for higher-flow filtration. Frost stocks 20-inch sediment and carbon Big Blue cartridges.
Can I use any fridge filter from the same brand?
No. One brand may use several different filter models. Match the part number or explicitly confirmed compatibility.
Does a coffee filter replace descaling?
Not necessarily. Follow the coffee-machine manufacturer’s descaling and maintenance instructions even with a filter installed.
Where can I buy replacement filters in South Africa?
Frost supplies domestic and commercial cartridges for RO, Big Blue, PM systems, fridges, coffee machines, fountains and chillers.
MATCH THE SYSTEM. MATCH THE JOB.
Find the Right Replacement Filter
A correct replacement matches both the physical system and the treatment function it is intended to perform.