How to Choose the Right Water Filter Cartridge: Sediment, Carbon and Big Blue Filter Guide

The right water filter cartridge should be selected based on what you want to remove from the water, how much flow is required, what filter housing size you have, and whether the application is for drinking water, whole house filtration, commercial use or light industrial water treatment.

For most systems, sediment filters are used first to remove dirt, rust, sand and suspended solids. Carbon filters are then used to reduce chlorine, taste, odour and certain organic compounds. Big Blue filter cartridges are commonly used when higher flow rate, larger capacity and lower pressure drop are required.

## Quick Answer: How Do You Choose the Right Water Filter Cartridge?

Choose a sediment filter if you need to remove visible particles, dirt, rust, sand or suspended solids.

Choose a carbon filter if you need to reduce chlorine, taste, odour or organic contaminants.

Choose a Big Blue cartridge if you need higher flow rate, larger capacity or whole house filtration.

Choose a smaller 10 inch standard cartridge if the system is for low-flow drinking water, under-sink filtration or compact point-of-use use.

The best cartridge depends on:

- Water source
- Contaminants to be removed
- Required flow rate
- Filter housing size
- Micron rating
- Pressure drop
- Cartridge service life
- Whether the filter protects an RO membrane
- Whether the application is residential, commercial or light industrial

## Water Filter Cartridge Selection Guide

## What Is a Water Filter Cartridge?

A water filter cartridge is a replaceable filtration element installed inside a filter housing. As water passes through the cartridge, specific contaminants are removed or reduced depending on the cartridge type.

Water filter cartridges are commonly used in:

- Under-sink drinking water systems
- Whole house water filtration
- Commercial kitchens and cafés
- Rainwater tank filtration
- Reverse osmosis pre-treatment
- Boiler and cooling tower pre-treatment
- Light industrial water treatment
- Food and beverage applications

Different cartridges are designed for different purposes. A sediment cartridge does not perform the same function as a carbon cartridge, and a small under-sink cartridge is not always suitable for a whole house system.

## Step 1: Identify Your Water Source

The first step is to understand the water source.

Common water sources in Australia include:

- Mains water
- Rainwater tank water
- Bore water
- Surface water
- Recycled water
- Process water
- Commercial building water supply

Mains water may contain chlorine, taste and odour issues. Rainwater tank water may contain sediment, organic matter and microbiological risk. Bore water may contain hardness, iron, manganese, salinity or other minerals. Commercial and industrial water may require more specific treatment depending on the process.

The water source determines what cartridge type should be used and whether additional treatment is required.

## Step 2: Identify What You Want to Remove

Different filter cartridges remove different contaminants.

Sediment filters are used to reduce:

- Dirt
- Rust
- Sand
- Silt
- Suspended solids
- Fine particles

Carbon filters are used to reduce:

- Chlorine
- Taste
- Odour
- Some organic compounds
- Some colour and chemical smell

Specialty cartridges may be used for:

- Hardness reduction
- Deionisation
- Iron reduction
- Scale control
- Nitrate reduction
- Specific process water requirements

A common mistake is choosing a filter by appearance rather than treatment objective. The correct cartridge should be selected based on the actual water quality issue.

## Step 3: Choose the Correct Cartridge Size

Cartridge size affects flow rate, capacity and pressure drop.

Common cartridge sizes include:

- 10 inch x 2.5 inch standard cartridge
- 20 inch x 2.5 inch standard cartridge
- 10 inch x 4.5 inch Big Blue cartridge
- 20 inch x 4.5 inch Big Blue cartridge

A 10 inch standard cartridge is usually suitable for low-flow under-sink systems or small drinking water filters.

A 20 inch standard cartridge provides more capacity and longer service life than a 10 inch standard cartridge.

A 10 inch Big Blue cartridge provides higher flow and larger capacity than a standard 10 inch cartridge.

A 20 inch Big Blue cartridge is commonly used for whole house filtration, commercial systems and higher-flow applications.

## Cartridge Size Comparison

## Step 4: Choose the Right Micron Rating

Micron rating describes the approximate particle size the filter can remove.

Common sediment filter micron ratings include:

- 1 micron
- 5 micron
- 10 micron
- 20 micron
- 50 micron

A smaller micron rating removes finer particles but usually creates higher pressure drop and may block faster.

A larger micron rating allows higher flow and longer service life but removes fewer fine particles.

For many general sediment filtration applications, 5 micron is a common choice. For very dirty water, a larger micron rating may be used first to avoid rapid blockage. For finer filtration before RO systems, a lower micron rating may be selected depending on system requirements.

## Micron Rating Selection Guide

## Step 5: Choose Sediment, Carbon or Specialty Cartridge

The cartridge type should match the treatment purpose.

## Sediment Filter Cartridges

Sediment cartridges remove suspended particles from water. They are often used as the first stage of filtration.

Common sediment cartridge types include:

- Polypropylene spun sediment filters
- Pleated sediment filters
- String wound cartridges
- Melt blown cartridges

Sediment filters are commonly used before carbon filters, RO membranes, UV systems, pumps, solenoid valves and water-using equipment.

A sediment filter is usually the first cartridge to install when the water contains visible particles, rust, sand or dirt.

## Carbon Filter Cartridges

Carbon cartridges reduce chlorine, taste, odour and some organic contaminants.

Common carbon cartridge types include:

- Granular activated carbon cartridges
- Carbon block cartridges
- CTO carbon block cartridges

Carbon filters are commonly used for mains water, drinking water systems, whole house filtration and RO pre-treatment.

A carbon filter is important before many RO membranes because free chlorine can damage thin-film composite RO membranes.

## Specialty Filter Cartridges

Specialty cartridges are used when sediment and carbon filtration are not enough.

Examples include:

- Water softening resin cartridges
- Deionisation resin cartridges
- Mixed bed resin cartridges
- Colour-changing DI resin cartridges
- Scale reduction cartridges
- Iron reduction cartridges

These cartridges should be selected based on water testing and the required water quality.

## Step 6: Consider Flow Rate and Pressure Drop

Flow rate is one of the most important factors when choosing a cartridge.

If a cartridge is too small for the required flow, the result may be:

- Low water pressure
- Reduced flow at taps
- Shorter cartridge life
- Frequent blockage
- Poor system performance
- Customer complaints

For whole house and commercial systems, Big Blue cartridges are often preferred because they provide larger surface area, higher capacity and lower pressure drop compared with small standard cartridges.

For drinking water systems, smaller cartridges may be acceptable because the flow rate is much lower.

## Step 7: Consider Service Life and Replacement Frequency

A cartridge should be replaced before it becomes blocked, exhausted or ineffective.

Sediment filters are usually replaced when:

- Flow rate decreases
- Pressure drop increases
- The cartridge becomes dirty
- Water clarity declines
- The recommended replacement period is reached

Carbon filters are usually replaced when:

- Chlorine taste returns
- Odour returns
- The rated capacity is reached
- The cartridge has been in service too long
- The filter is protecting an RO membrane and chlorine breakthrough risk increases

Do not rely only on time. Cartridge life depends on water quality, flow rate and total usage volume.

## Step 8: Match the Cartridge to the Housing

A cartridge must match the filter housing size.

Before buying a replacement cartridge, check:

- Housing height
- Housing diameter
- Cartridge length
- Cartridge diameter
- Seal type
- End cap type
- Flow direction if applicable
- Maximum pressure rating
- Maximum temperature rating

For example, a 20 inch x 4.5 inch Big Blue cartridge will not fit a standard 20 inch x 2.5 inch housing.

The terms “10 inch”, “20 inch”, “standard” and “Big Blue” must be checked carefully before purchasing.

## Which Cartridge Is Best for Whole House Filtration?

For whole house filtration, a 20 inch Big Blue cartridge is often the best choice because it provides higher flow rate and larger capacity.

A common whole house setup may include:

- 20 inch Big Blue sediment filter
- 20 inch Big Blue carbon filter
- Optional specialty cartridge depending on water quality
- Additional treatment such as UV or RO if required

For Australian homes on mains water, a sediment filter plus carbon filter may help reduce rust, particles, chlorine taste and odour.

For rainwater tank systems, sediment filtration is usually important before any carbon, UV or additional treatment stage.

## Which Cartridge Is Best for Drinking Water?

For drinking water, a sediment filter followed by a carbon block filter is commonly used.

A typical drinking water cartridge setup may include:

- 5 micron sediment filter
- Carbon block filter
- RO membrane if dissolved salts reduction is required
- Post-carbon polishing filter if required

Carbon block cartridges are commonly used for drinking water because they provide finer filtration and good taste and odour reduction at lower flow rates.

## Which Cartridge Is Best Before an RO System?

For RO pre-treatment, sediment and carbon filtration are commonly used.

A typical RO pre-treatment setup may include:

- Sediment filter to remove particles
- Carbon filter to reduce chlorine
- Antiscalant or softening if scaling risk is high
- Additional pre-treatment depending on feed water quality

The carbon filter is especially important when the RO membrane is sensitive to chlorine. If the carbon cartridge is exhausted or undersized, chlorine may pass through and damage the membrane.

## Common Cartridge Selection Mistakes

Common mistakes include:

- Choosing a cartridge only by price
- Using a small cartridge for a high-flow system
- Choosing too fine a micron rating for dirty water
- Using carbon without sediment protection
- Not replacing carbon filters before chlorine breakthrough
- Assuming all 10 inch or 20 inch filters are the same
- Using drinking water cartridges for whole house flow
- Replacing cartridges without identifying the water quality issue
- Installing the wrong cartridge size in the housing
- Ignoring pressure drop

Correct cartridge selection improves water quality, protects downstream equipment and reduces operating problems.

## Common Applications in Australia

Water filter cartridges are commonly used in Australia for:

- Under-sink drinking water filters
- Whole house filtration systems
- Rainwater tank filtration
- Commercial kitchens
- Cafés and restaurants
- Ice machines and coffee machines
- Food and beverage facilities
- Boiler feedwater pre-treatment
- Cooling tower make-up water
- RO system pre-treatment
- Light industrial process water

Australian applications can vary significantly depending on the water source. Mains water, rainwater, bore water and process water may all require different cartridge selections.

## Crystwater Recommendation

At Crystwater, we recommend choosing water filter cartridges based on application, water quality and system performance requirements rather than simply matching the cheapest cartridge available.

Before selecting a cartridge, confirm:

- What is the water source?
- What contaminants need to be removed?
- Is the system for drinking water, whole house, commercial or industrial use?
- What flow rate is required?
- What filter housing size is installed?
- What micron rating is suitable?
- Is pressure drop a concern?
- Is the cartridge protecting an RO membrane or other equipment?
- How often can the cartridge be replaced?
- Is a sediment filter required before a carbon filter?

For low-flow drinking water systems, standard cartridges may be suitable.

For whole house, commercial and light industrial systems, Big Blue cartridges are often a better option because they provide higher capacity and better flow performance.

## Frequently Asked Questions

### What water filter cartridge do I need?

You need a cartridge that matches your water source, contaminant type, housing size and required flow rate. Sediment filters remove particles, carbon filters reduce chlorine, taste and odour, and Big Blue cartridges are used for higher-flow applications.

### What is the difference between sediment and carbon filters?

A sediment filter removes dirt, rust, sand and suspended solids. A carbon filter reduces chlorine, taste, odour and certain organic compounds. Many systems use both, with sediment filtration installed before carbon filtration.

### What is a Big Blue filter cartridge?

A Big Blue filter cartridge is a larger diameter cartridge, commonly 4.5 inches wide, used in Big Blue style housings. It provides higher flow capacity and longer service life than smaller standard cartridges.

### Is a 5 micron or 1 micron filter better?

A 1 micron filter removes finer particles, but it may reduce flow and block faster. A 5 micron filter is often a practical choice for general sediment filtration. The best option depends on water quality and flow requirement.

### Should the sediment filter go before the carbon filter?

Yes. In most systems, the sediment filter should be installed before the carbon filter. This helps protect the carbon cartridge from dirt and particles and may extend its service life.

### Can I use a carbon filter for dirty water?

A carbon filter is not designed as the main filter for dirty water. If the water contains sediment, rust, sand or particles, a sediment filter should usually be installed before the carbon filter.

### Which cartridge is best for whole house water filtration?

A 20 inch Big Blue sediment filter and 20 inch Big Blue carbon filter are commonly used for whole house filtration because they provide higher flow rate and larger capacity than smaller cartridges.

### Which cartridge is best for under-sink drinking water?

For under-sink drinking water, a standard sediment filter followed by a carbon block filter is commonly used. If dissolved salts reduction is required, an RO membrane may also be included.

### How often should water filter cartridges be replaced?

Replacement depends on water quality, flow rate and usage volume. Sediment filters should be replaced when flow drops or pressure increases. Carbon filters should be replaced before taste, odour or chlorine returns.

### Can the wrong cartridge reduce water pressure?

Yes. A cartridge that is too small, too fine or blocked can reduce water pressure. For high-flow applications, larger cartridges such as 20 inch Big Blue filters are often preferred.

## Final Summary

Choosing the right water filter cartridge depends on the water source, contaminant type, required flow rate, housing size, micron rating and application.

Sediment filters are used to remove dirt, rust, sand and suspended solids.

Carbon filters are used to reduce chlorine, taste, odour and certain organic contaminants.

Big Blue cartridges are commonly used for whole house, commercial and light industrial systems because they provide higher flow rate, larger capacity and longer service life.

For the best result, choose the cartridge based on the actual treatment objective rather than appearance or price alone.

Need Help Selecting the Right Water Treatment Product?

Crystwater provides practical product selection support for water filtration cartridges, activated carbon, ion exchange resin, RO membranes and commercial water treatment systems across Australia.

Whether you are replacing filter cartridges, comparing resin options, selecting RO membranes or planning a commercial water treatment system, our engineer-led support can help you choose the right solution.

Contact Crystwater Shop Water Treatment Products