๐ What’s in this guide
- What does “micron rating” actually mean?
- How 5 micron and 20 micron filters differ
- When to use each micron rating
- Practical use cases & real-world scenarios
- Multi-stage filtration: using both together
- Performance, flow rate & pressure drop
- Amazon product comparison table
- eBay AU product comparison table
- AliExpress product comparison table
- Platform comparison: Amazon vs eBay vs AliExpress
- Buying guide & selection checklist
- Frequently asked questions
- Final verdict & recommendation
If you’ve ever stood in front of a wall of filter cartridges at a hardware store โ or scrolled through dozens of listings online โ you’ve almost certainly asked yourself: what’s the difference between a 5 micron and a 20 micron filter, and which one do I actually need?
The answer isn’t just about the size of the number. It determines how much sediment your filter catches, how quickly it clogs, how much it restricts your water flow, and ultimately โ how long the cartridge lasts before needing replacement. Get it wrong and you’re either replacing filters every few weeks, or letting particles through that could damage your pipes, appliances, or downstream filters.
This guide covers everything: the science, the practical scenarios, a full comparison of popular products on Amazon AU and eBay AU โ all with affiliate links so you can buy with confidence.
๐ท CC BY-SA ยท Wikimedia Commons
= 1 millionth of a metre
finer than 20 micron
particle removal (both ratings)
months avg filter life
1. What does “micron rating” actually mean?
A micron (symbol: ฮผm) is a unit of measurement equal to one millionth of a metre, or 0.001 millimetres. To put that in perspective, a single human hair is approximately 70 microns wide. A grain of fine sand is around 90 microns. Red blood cells are about 8 microns.
When a filter is rated at 5 microns, it means it can trap particles that are 5 microns or larger in diameter. A 20-micron filter traps particles 20 microns and larger โ meaning it lets through anything smaller than 20 microns.
Counterintuitively, a lower micron number is a tighter filter. A 5 micron filter catches smaller particles than a 20 micron filter. Think of it like mesh: the smaller the hole size, the finer the screen.
Nominal vs Absolute Micron Rating
There are two types of micron ratings you’ll see on product labels, and this distinction matters enormously when choosing a filter:
| Rating Type | What it means | Particle removal | Best for |
|---|---|---|---|
| Nominal | Removes ~85% of particles at the stated size | ~85% efficiency | Pre-filtration, general sediment removal |
| Absolute | Removes 99.9%+ of particles at the stated size | โฅ99.9% efficiency | Critical applications, drinking water, food service |
Most household sediment cartridges you’ll find on Amazon and eBay are nominal rated. For drinking water or medical/food applications, always look for absolute rated filters โ they cost more but provide the certainty you need.
What particles are we actually talking about?
| Contaminant / Particle | Approximate Size (ฮผm) | Caught by 20ฮผm? | Caught by 5ฮผm? |
|---|---|---|---|
| Coarse sand | 500โ2000 ฮผm | โ Yes | โ Yes |
| Fine sand / grit | 90โ500 ฮผm | โ Yes | โ Yes |
| Silt & sediment | 4โ90 ฮผm | Partial | โ Yes (most) |
| Rust particles | 5โ200 ฮผm | Partial | โ Yes |
| Algae | 10โ100 ฮผm | Partial | โ Yes (most) |
| Cysts (Giardia) | 8โ12 ฮผm | โ No | โ Yes |
| Fine clay particles | 1โ4 ฮผm | โ No | โ No (need 1ฮผm) |
| Bacteria (most) | 0.5โ5 ฮผm | โ No | Marginal |
2. How 5 micron and 20 micron filters differ
Beyond the particle size they capture, these two filter ratings differ in several practical, day-to-day ways that affect your experience as a homeowner, farmer, or facility manager.
- โ Catches very fine particles, silt, most rust flakes
- โ Better protection for RO membranes and carbon blocks
- โ Suitable as drinking water pre-filter
- โ Catches Giardia cysts (8โ12 ฮผm)
- โ Clogs faster in high-sediment water
- โ Higher pressure drop across filter
- โ Shorter lifespan in dirty water conditions
- โ More frequent replacement needed
- โ Excellent for high-sediment bore, tank & dam water
- โ Much longer filter life in dirty conditions
- โ Lower pressure drop, better flow rate
- โ Cheaper to run over time in heavy-sediment scenarios
- โ Ideal first stage in multi-stage systems
- โ Misses fine silt, fine rust, and smaller particles
- โ Not suitable as a standalone drinking water filter
- โ Does not catch Giardia or Cryptosporidium cysts
Every filter restricts water flow to some degree. A 5 micron filter creates more resistance than a 20 micron filter because the pores are smaller. In low-pressure systems (like tank gravity-fed systems or caravans), this can mean a noticeably weaker flow. A 20 micron filter in these systems maintains much better water pressure.
3. When to use each micron rating
This is the most practical question, and the answer depends on your water source, your intended use, and what downstream equipment you’re protecting. Here’s the definitive breakdown.
Use a 5 Micron filter whenโฆ
-
1
You’re on town/municipal mains water
Mains water is already treated and relatively clean. A 5 micron filter is perfect as a pre-filter before a carbon block or under-sink system to catch remaining sediment, rust from old pipes, and fine particles.
-
2
You’re feeding an RO (reverse osmosis) system
RO membranes are expensive and sensitive. A 5 micron sediment pre-filter is the standard first stage in any RO system to protect the membrane from fouling and extend its life significantly.
-
3
You need drinking-water quality filtration
If your filtered water is for drinking or cooking directly from the filter output, 5 micron provides a much higher level of particle removal than 20 micron, including catching algae and most cysts.
-
4
Your water source has light-to-moderate sediment
If your water isn’t heavily laden with sand and silt โ such as rainwater tanks with good first-flush systems, or treated bore water โ a 5 micron filter will handle it well without clogging too quickly.
Use a 20 Micron filter whenโฆ
-
1
You have high-sediment bore, dam or river water
Untreated groundwater and surface water in Australia often carries significant loads of sand, clay, and organic matter. A 20 micron filter handles this bulk sediment without blinding (clogging completely) within days.
-
2
You’re protecting irrigation systems and equipment
For irrigation lines, pumps, and valves, a 20 micron filter protects nozzles and drippers from blockage without the maintenance burden of a finer filter in an agricultural context.
-
3
You’re running a multi-stage system (first stage)
The most cost-effective setup uses a 20 micron first stage to capture the bulk of coarse sediment cheaply, followed by a 5 micron second stage for fine polishing. This dramatically extends the life of your 5 micron cartridge.
-
4
You need high flow rate with minimal pressure loss
For applications where water volume matters โ like filling stock troughs, fire-fighting tanks, or washing vehicles โ a 20 micron filter maintains far better flow rate than a 5 micron equivalent.
4. Practical use cases & real-world scenarios
Here’s how to match your specific situation to the right micron rating. These are the most common Australian water use scenarios:
๐ท CC BY-SA ยท Wikimedia Commons
Suburban Home (Mains Water)
Town water is pre-treated. Primary concerns are rust from old pipes and chlorine taste. A 5 micron sediment pre-filter before a carbon block is ideal.
Use: 5 Micron
Rural Property / Farm (Bore Water)
Bore water often carries high loads of sand, iron, and minerals. Start with 20 micron as first stage, then 5 micron as second stage for best results.
Use: 20ฮผm โ 5ฮผm
Caravan / Off-Grid Living
Water sources vary wildly. A 20 micron protects the pump and lines when hooking up to unknown supplies. Add 5 micron for drinking water.
Use: 20ฮผm + 5ฮผm
Rainwater Tank System
Tank water contains roof runoff: leaves, bird matter, fine grit. A 20 micron pre-filter before a 5 micron final filter protects the system efficiently.
Use: 20ฮผm โ 5ฮผm
RO (Reverse Osmosis) System
The RO membrane requires fine pre-filtration. A dedicated 5 micron sediment cartridge as Stage 1 is the industry standard to protect the membrane.
Use: 5 Micron
Commercial / Industrial
Depends on process. Food processing needs 5 micron or finer. Cooling towers and industrial equipment pre-filtration often use 20โ50 micron as first stage.
Application dependent
Aquarium / Aquaculture
Aquarium top-up water benefits from 5 micron filtration to remove chlorine particles and fine debris before entering sensitive aquatic systems.
Use: 5 Micron
Dam / River Water
Surface water has very high sediment loads and potential biological matter. Use a 50 micron or 20 micron coarse pre-filter first, then step down to 5 micron.
Use: 50ฮผm โ 20ฮผm โ 5ฮผm
5. Multi-stage filtration: using both together
The most effective and cost-efficient approach in most Australian homes and rural properties is to use both micron ratings in a staged system. This is called graduated or staged filtration, and it’s the professional approach used in everything from suburban under-sink systems to industrial water treatment plants.
Always filter coarse first, fine last. A 20 micron filter upstream removes the bulk sediment cheaply and quickly, protecting the more expensive 5 micron filter downstream. This can extend the life of your 5 micron cartridge by 3โ5ร or more in high-sediment water.
Recommended setups by scenario
| Water Source | Stage 1 | Stage 2 | Stage 3 (optional) | Purpose |
|---|---|---|---|---|
| Mains / Town Water | 5 ฮผm Sediment | Carbon Block | UV or RO | Rust, chlorine, taste |
| Rainwater Tank | 20 ฮผm Sediment | 5 ฮผm Sediment | Carbon + UV | Roof debris, grit, bacteria |
| Bore / Well Water | 20 ฮผm Sediment | 5 ฮผm Sediment | Iron filter or RO | Sand, iron, minerals |
| Dam / River | 50 ฮผm Sediment | 20 ฮผm Sediment | 5 ฮผm + UV | Heavy sediment + pathogens |
| RO Drinking System | 5 ฮผm Sediment | Carbon Block | RO Membrane | Membrane protection |
6. Performance, flow rate & pressure drop
One of the most misunderstood aspects of filter selection is the relationship between micron rating and system performance. Here’s what you need to know before you commit to a filter size.
Pressure Drop
Pressure drop (also called differential pressure or ฮP) is the difference in water pressure between the inlet and outlet of a filter. A higher pressure drop means your filter is restricting flow more. This affects:
๐ท CC BY-SA
๐ท CC BY-SA
- Water pressure at your taps and showers
- Flow rate to appliances like washing machines and dishwashers
- How quickly tanks or sumps fill
- Performance of downstream filters and membranes
| Factor | 5 Micron Filter | 20 Micron Filter |
|---|---|---|
| Initial pressure drop (new filter) | Moderate (~1โ2 psi) | Low (~0.5โ1 psi) |
| Pressure drop when loaded with sediment | High (clogs faster) | Moderate (holds more before clogging) |
| Flow rate restriction | Moderate to high | Low to moderate |
| Recommended change pressure (max ฮP) | 15โ20 psi | 15โ20 psi |
| Filter life in clean municipal water | 3โ6 months | 6โ12 months |
| Filter life in high-sediment bore/tank water | 2โ8 weeks | 1โ4 months |
On heavily contaminated bore or dam water, a 5 micron filter used alone may last only weeks and could cost you hundreds of dollars per year in replacements. Using a 20 micron as a sacrificial pre-filter โ which is cheaper per cartridge โ can reduce your annual filtration cost by 40โ60% while maintaining the same output water quality.
7. Amazon product comparison
The following products are available on Amazon AU and represent a cross-section of popular, highly-rated 5 micron and 20 micron sediment filter cartridges. All links include our affiliate tag.
5 Micron โ Fine Filtration Cartridges
| Product | Micron / Size | Key Features | Rating | Link |
|---|---|---|---|---|
|
SimPure Sediment Filter 2-Pack
Whole house big blue housing replacement. Food-grade 100% polypropylene. Universal 20″ร4.5″ fit. Compatible with WGB22B, WGB32B, AP802, BB20B and most big-blue housings. Up to 15,000 gallons per cartridge. Replace every 3โ6 months.
|
5 ฮผm ยท 20″ร4.5″ | 99% particle removal ยท Long 15,000 gal life ยท Whole house big-blue compatible | โ โ โ โ โ | Buy โ |
|
PUREPLUS 5 Micron Sediment Filter 6-Pack
Standard 20″ร2.5″ slim housing and RO pre-filtration. IAPMO, CSA, BPA-free and WaterMark certified. 20+ years industry expertise. Up to 13,000 gallons per cartridge. California-headquartered manufacturer. Excellent value 6-pack.
|
5 ฮผm ยท 20″ร2.5″ | IAPMO + CSA certified ยท BPA-free ยท 13,000 gal ยท Value 6-pack | โ โ โ โ โ | Buy โ |
|
Membrane Solutions String Wound 5 Micron 6-Pack
Unique honeycomb structure increases dirt-holding capacity and maximises filter life. Made from non-toxic, tasteless 100% polypropylene. Fits most 20″ filter housings, RO systems, and whole house filtration units. Replace 2โ3 times per year.
|
5 ฮผm ยท 20″ร2.5″ | Honeycomb dirt-holding ยท Universal fit ยท Well water rated | โ โ โ โ ยฝ | Buy โ |
|
Aquaboon 5 Micron Big Blue Filter 2-Pack
Graded pore structure ensures zero pressure drop for continuous whole-home flow. Engineered for high flow rates. Heavy-duty melt-blown polypropylene resists chemicals and corrosion. Compatible with most 20″ร4.5″ big blue housings. 4โ6 month service life.
|
5 ฮผm ยท 20″ร4.5″ | No pressure drop design ยท Chemical resistant ยท High-flow | โ โ โ โ ยฝ | Buy โ |
20 Micron โ Coarse Pre-Filtration Cartridges
| Product | Micron / Size | Key Features | Rating | Link |
|---|---|---|---|---|
|
Ronaqua 20 Micron NSF Certified Filter 6-Pack
NSF/ANSI Standard 42 certified by IAPMO R&T for material safety. 4-layer gradient density structure removes sediment, rust, sand, dirt, and silt from well and municipal water. Premium food-grade 100% polypropylene with melt-blown technology. Fits most 10″ RO and whole-house housings.
|
20 ฮผm ยท 10″ร2.5″ | NSF/ANSI 42 certified ยท 4-layer gradient ยท Melt-blown PP | โ โ โ โ โ | Buy โ |
|
Membrane Solutions 20 Micron Filter 6-Pack
Multi-layer gradient density design for deep sediment filtration with higher dirt-holding capacity than standard filters. ISO9001, NSF-tested, and BPA-free. Service life 10,000โ15,000 gallons. Universal fit for Culligan P5, Aqua-Pure AP110, GE FXUSC, Whirlpool WHKF-GD05 and more.
|
20 ฮผm ยท 10″ร2.5″ | Multi-layer gradient ยท ISO9001 ยท 10โ15k gal life ยท Universal | โ โ โ โ ยฝ | Buy โ |
|
AO Smith 20 Micron Sediment Filter 2-Pack
Genuine AO Smith replacement filter for AO-WH-PREV and AO-WH-PRE whole house systems. Designed for households of 1โ4 people. Reduces sediment smaller than the naked eye. No plumber required for replacement. Replace every 3 months for optimal performance.
|
20 ฮผm ยท 10″ร2.5″ | OEM AO Smith ยท Tool-free install ยท 3-month replacement ยท 1โ4 person homes | โ โ โ โ โ | Buy โ |
|
Superior Filters 20 Micron Big Blue 6-Pack
Universal fit for standard 20″ร4.5″ whole house filter housings. Ideal as pre-filter for RO systems, UV sterilisers, and water softeners. Rigorously tested to industry standards. Captures dirt, rust, sand, and microplastics. Durable polypropylene construction resistant to chemicals and temperature variation.
|
20 ฮผm ยท 20″ร4.5″ | Universal 20″ร4.5″ ยท Pre-filter for UV/RO ยท Value 6-pack | โ โ โ โ | Buy โ |
8. eBay AU product comparison
eBay Australia has strong representation from Australian-based sellers including Shield Filter, Filter Systems Australia, and ITM โ all offering locally stocked products with fast domestic shipping and WaterMark compliance where relevant.
5 Micron โ Fine Filtration (Australian Sellers)
| Product | Micron / Size | Key Features | Seller Rating | Link |
|---|---|---|---|---|
|
ITM Whole House 20″ร4.5″ 5 Micron Sediment Cartridge
Australian seller. Fits standard 20″ร4.5″ big blue housings. Excellent for whole house pre-filtration on mains or lightly contaminated tank water. Polypropylene construction. Fast domestic shipping. Afterpay available for eligible buyers.
|
5 ฮผm ยท 20″ร4.5″ | AU seller ยท Afterpay ยท Big blue compatible ยท Fast ship | โ โ โ โ ยฝ | Buy โ |
|
Shield Filter 2-Set Sediment + Carbon 5 Micron 10″
Australian Standard WaterMark Tested and Certified. Shield Filter is a leading AU specialist brand. Combo pack includes sediment AND carbon cartridge. Ideal for undersink or bench-top systems. Compatible with most standard 10″ housings. 98.2% positive feedback from 38,000+ sales.
|
5 ฮผm ยท 10″ร2.5″ | WaterMark certified ยท Combo sediment+carbon ยท 38K+ sales | โ โ โ โ โ | Buy โ |
|
Filter Systems Australia 5ร Poly Spun Sediment 10″ร2.5″
Australian-created product range, carefully selected for quality. Ideal for bore, tank, river and dam water filtration. 5-pack for value. Polypropylene spun sediment filter. Reviewed as “super quick delivery” by multiple verified buyers. Great for caravan and off-grid use.
|
5 ฮผm ยท 10″ร2.5″ | AU-made ยท 5-pack value ยท Bore & tank rated ยท Off-grid | โ โ โ โ โ | Buy โ |
|
20″ร4.5″ 5 Micron CTO Carbon Block Big Blue Cartridge
Carbon block filter that combines 5 micron sediment removal with chlorine and taste/odour reduction in a single cartridge. Perfect upgrade from pure sediment filters for mains water users who want both sediment AND chemical protection in one stage. Big blue 20″ร4.5″ housing compatible.
|
5 ฮผm CTO ยท 20″ร4.5″ | Sediment + chlorine removal ยท CTO carbon block ยท 2-in-1 | โ โ โ โ ยฝ | Buy โ |
20 Micron โ Coarse Pre-Filtration (Australian Sellers)
| Product | Micron / Size | Key Features | Seller Rating | Link |
|---|---|---|---|---|
|
ITM Whole House 10″ร4.5″ 20 Micron Sediment Cartridge
Australian seller. Standard 10″ร4.5″ big blue housing replacement for coarse pre-filtration. Excellent for bore water, tank water, and rural properties with high sediment loads. Polypropylene construction. Afterpay eligible. Delivery tracked and fast from Australian warehouse.
|
20 ฮผm ยท 10″ร4.5″ | AU seller ยท 10″ร4.5″ big blue ยท Bore & tank water ยท Afterpay | โ โ โ โ ยฝ | Buy โ |
|
10ร 20″ร4.5″ 20 Micron Pleated Washable Sediment Filter
Washable and reusable pleated filter โ a major cost advantage. 10-pack for serious value. Very popular for pool, tank, river, dam and bore water. Available in 5, 10, 20, and 30 micron. Pleated design maximises filtration area for higher capacity and longer service intervals before washing.
|
20 ฮผm ยท 20″ร4.5″ | Washable + reusable ยท 10-pack value ยท Dam/bore/pool rated | โ โ โ โ โ | Buy โ |
|
Membrane Solutions Multi-Micron 10″ร4.5″ Pleated Filter
Available in 1, 5, 10, 20, and 50 micron from the same listing โ select 20 micron for coarse pre-filtration. Pleated polyester design for high dirt capacity and superior flow rate vs melt-blown. Membrane Solutions is a US-owned company with 20+ years of residential and industrial filtration expertise.
|
20 ฮผm ยท 10″ร4.5″ | Choose your micron ยท Pleated design ยท High flow ยท 20yr brand | โ โ โ โ ยฝ | Buy โ |
|
Shield Filter Whole House 20 Micron Sediment 10″ร2.5″
From Shield Filter โ one of Australia’s most trusted water filtration brands with WaterMark certification. Ideal as a coarse pre-filter before a finer sediment or carbon stage. Compatible with standard 10″ร2.5″ housings. Excellent for protecting downstream filters and extending system lifespan on bore or tank supply.
|
20 ฮผm ยท 10″ร2.5″ | WaterMark certified ยท Shield brand ยท AU stocked ยท Pre-filter | โ โ โ โ โ | Browse Store โ |
9. AliExpress product comparison
AliExpress is a great source for budget-friendly sediment filter cartridges shipped directly from manufacturers โ often at 30โ60% less than Amazon or eBay prices. The trade-off is longer shipping times (typically 2โ5 weeks to Australia) and variable quality, so stick to sellers with high ratings and large order counts. All links below include your affiliate tracking.
Always check: seller feedback (aim for 95%+), order count (500+ orders is a good sign), and whether the listing ships from an AU or CN warehouse. Look for “AliExpress Standard Shipping” for the best balance of price and delivery speed to Perth/AU.
5 Micron โ Fine Filtration Cartridges
| Product | Micron / Size | Key Features | Est. Rating | Affiliate Link |
|---|---|---|---|---|
|
ATWFS 5 Micron PP Cotton Sediment Filter 4-Pack 10″ร2.5″
Pure spun polypropylene construction. No binders, wetting agents, or solvents. Ideal for Stage 1 pre-filtration in RO systems, undersink units, and whole house 10″ slim housings. Removes sand, rust, silt and dirt. Very popular listing with thousands of orders. Budget-friendly 4-pack for frequent replacers.
|
5 ฮผm ยท 10″ร2.5″ | Pure PP ยท No binders ยท RO Stage 1 ยท Budget 4-pack | โ โ โ โ ยฝ | Buy โ |
|
PP Sediment Filter 20″ 5 Micron Polypropylene 3-Pack
20-inch standard slim (2.5″ OD) polypropylene replacement cartridge. Fits most 20″ slim-line housings worldwide. Melt-blown construction for gradient density filtration. Food-safe materials. Great value 3-pack for whole house or point-of-use pre-filtration on lightly contaminated mains or tank water.
|
5 ฮผm ยท 20″ร2.5″ | 20″ slim ยท Melt-blown ยท Food safe ยท 3-pack value | โ โ โ โ | Buy โ |
|
Whole House 2.5″ร10″ Pleated Sediment 5 Micron โ Washable & Reusable
Pleated polyester design provides larger surface area for superior dirt-holding capacity compared to melt-blown cartridges. Washable and reusable โ rinse under running water to extend filter life significantly. Fits all standard 10″ร2.5″ housings. Excellent cost-per-use for high-sediment rainwater or bore water pre-filtration.
|
5 ฮผm ยท 10″ร2.5″ | Pleated + washable ยท High dirt-hold ยท Reusable ยท Best value/use | โ โ โ โ ยฝ | Buy โ |
|
Coronwater Quick Change 5 Micron PP Sediment Cartridge
Quick-change design for tool-free cartridge swap without shutting off water. Compact 2.5″ร10″ size. Pure polypropylene melt-blown media. Suitable for undersink quick-change filter systems and compact RO pre-filter stages. Low-cost replacement with free worldwide shipping. Popular with AU buyers for caravan and off-grid use.
|
5 ฮผm ยท Quick-Change | Quick-change ยท Tool-free swap ยท Compact ยท Off-grid friendly | โ โ โ โ | Buy โ |
20 Micron โ Coarse Pre-Filtration Cartridges
| Product | Micron / Size | Key Features | Est. Rating | Affiliate Link |
|---|---|---|---|---|
|
20 Micron Whole House 4.5″ร20″ Pleated Sediment โ Washable & Reusable
Big blue 20″ร4.5″ washable pleated sediment cartridge at a fraction of the price of Western brands. Installs quickly into all standard 20″ร4.5″ big blue housings. Replace every 3โ6 months or wash and reuse. Very popular for Australian rural properties, pool pre-filtration, bore water, and rainwater tanks. Free worldwide shipping available.
|
20 ฮผm ยท 20″ร4.5″ | Big blue ยท Washable ยท Bore & tank rated ยท Free ship | โ โ โ โ ยฝ | Buy โ |
|
2.5″ร10″ Compatible Pleated Filter 20 Micron โ Dirt & Sediment
Slim 10″ร2.5″ pleated replacement in 20 micron for coarse pre-filtration before a finer stage. Suits standard slim housings, RO system pre-filters, and undersink pre-filter stages. Polyester pleated construction for washability. Great choice as a first-stage cartridge in a dual-filter setup protecting a 5 micron downstream cartridge.
|
20 ฮผm ยท 10″ร2.5″ | Slim housing ยท Pleated polyester ยท Pre-filter ยท RO compatible | โ โ โ โ | Buy โ |
|
PP Sediment Filter 2pcs 5″ 20 Micron Polypropylene Cartridge
Compact 5-inch cartridge in 20 micron for smaller filter housings, inline pre-filters, and caravan/RV/boat water systems. Pure polypropylene โ no chemical additives. Great for low-flow systems where a large cartridge would cause excessive pressure drop. 2-pack value with free shipping to Australia.
|
20 ฮผm ยท 5″ร2.5″ | Compact size ยท Caravan/RV/boat ยท 2-pack ยท Low pressure drop | โ โ โ โ | Buy โ |
|
10″ Reusable Empty Clear Cartridge Housing + 20 Micron Fill Media
Refillable 10″ clear housing you can pack with your own filter media โ order with 20 micron polypropylene loose media for a fully customisable pre-filter stage. Ideal for DIY multi-stage setups, aquaponics, aquarium pre-filtration, and experimental filter configurations. Suits all standard 10″ housing thread types.
|
20 ฮผm ยท 10″ Refillable | DIY refillable ยท Clear housing ยท Custom media ยท Aquaponics/aquarium | โ โ โ โ | Buy โ |
10. Platform comparison: Amazon vs eBay AU vs AliExpress
Not sure which platform to buy from? Here’s a direct comparison to help you choose based on your priorities โ speed, price, brand assurance, or local support.
| Factor | ๐ Amazon AU | ๐ eBay AU | ๐ AliExpress |
|---|---|---|---|
| Typical delivery to Perth | 2โ7 days (Prime) | 2โ5 days (AU sellers) | 2โ5 weeks (CN ship) |
| Price vs quality ratio | Mid โ good brands | Mid โ AU certified | Best price ยท variable quality |
| Australian WaterMark certified products | Some (check listing) | Yes (Shield, ITM etc.) | Rarely |
| NSF/ANSI certified options | Yes (Ronaqua, PUREPLUS) | Yes (Ronaqua, Shield) | Limited โ check listing |
| Multi-pack value | Excellent 6-packs | Good 4โ10 packs | Best bulk pricing |
| Washable/reusable options | Available | Good selection | Excellent selection |
| Returns & buyer protection | Excellent | Good (eBay Money Back) | AliExpress Buyer Protection |
| Best for | Fast delivery, trusted brands, RO systems | AU compliance, local support, rural AU | Bulk buying, budget builds, DIY systems |
Many experienced filter users buy their housing systems from Amazon or eBay AU (for WaterMark compliance and warranty) and then stock up on replacement cartridges from AliExpress in bulk. A 10-pack of washable 20 micron pleated cartridges from AliExpress at ~$2โ3 each can save you $100+ per year vs buying singles locally โ especially for bore/tank applications where you’re replacing every 4โ8 weeks.
11. Buying guide & selection checklist
Before you buy, use this checklist to make sure you’re selecting the right filter for your specific situation. Answer each question and follow the recommendation.
| Question | If YES โ recommendation | If NO โ recommendation |
|---|---|---|
| Is your water source mains/municipal? | 5 micron is sufficient as pre-filter | Consider 20 micron first stage |
| Is your water visibly cloudy or brown? | Start with 20 micron to handle bulk sediment | 5 micron likely adequate alone |
| Are you feeding an RO membrane? | Use 5 micron sediment as mandatory Stage 1 | Match micron to your water source |
| Is this for drinking water directly? | 5 micron minimum; ideally + carbon block | 20 micron acceptable for non-potable use |
| Are you on a low-pressure gravity system? | Use 20 micron to maintain flow rate | Either rating suitable |
| Do you want washable/reusable filters? | Choose pleated polyester design (both ratings available) | Standard melt-blown or string-wound fine |
| Is this an agricultural / irrigation use? | 20 micron preferred โ higher flow, longer life | Match micron to application |
| Do you have a Big Blue (4.5″ diameter) housing? | Ensure product is 10″ร4.5″ or 20″ร4.5″ | Standard slim is 10″ร2.5″ or 20″ร2.5″ |
Whether you choose 5 or 20 micron, buying 4โ6 pack cartridges is almost always 30โ50% cheaper per unit than single packs. Since filters need replacing every 3โ6 months, a 6-pack covers your household for 18 months to 3 years and saves you frequent re-ordering.
12. Frequently asked questions
๐ Final Verdict
There’s no single winner between 5 and 20 micron โ the right choice depends entirely on your water source and application. Use this simple guide to make the call instantly:
Bore/tank/dam water โ 20 Micron first
Best practice โ Use both in stages
Budget buying โ AliExpress bulk packs
AU compliance + fast ship โ eBay AU
Trusted brands + RO โ Amazon AU
Our top pick for most Australian households is a dual-stage setup: a 20 micron big blue cartridge as Stage 1 feeding a 5 micron slim cartridge as Stage 2. This costs around AU $40โ60 per year in cartridges and delivers water quality suitable for all household uses.
๐ฐ Annual filter cost estimator
Use this quick reference to estimate your yearly cartridge spend based on your setup and water source. Prices are approximate Australian market rates.
| Setup | Water Source | Est. Changes/Year | Cost/Cartridge (AU) | Est. Annual Cost |
|---|---|---|---|---|
| Single 5ฮผm slim (10″ร2.5″) | Mains | 2ร | ~$6โ10 | ~$12โ20/yr |
| Single 5ฮผm slim (10″ร2.5″) | Tank/Bore | 6โ12ร | ~$6โ10 | ~$36โ120/yr |
| Single 20ฮผm big blue (20″ร4.5″) | Bore/Dam | 3โ4ร | ~$10โ15 | ~$30โ60/yr |
| Dual stage: 20ฮผm โ 5ฮผm | Tank/Bore | 3โ4ร each | ~$8โ12 each | ~$50โ100/yr |
| Washable pleated 20ฮผm (AliExpress) | Bore/Dam/Pool | Wash 4ร, replace 1ร | ~$3โ5 | ~$5โ10/yr |
| Full 3-stage RO system (5ฮผm+carbon+RO) | Any | 2ร sediment, 1ร RO membrane/3yr | ~$15โ30 set | ~$60โ120/yr |
A reverse osmosis membrane costs AU $60โ150 and should last 2โ3 years with proper pre-filtration. Without a 5 micron sediment pre-filter, it may foul within 6โ12 months on dirty water. Spending $20/year on a sediment pre-filter can save you $50โ100/year in membrane replacements โ and that’s before accounting for improved flow rate and water quality.
Get our free Water Quality Checklist
A printable PDF with the 12-question diagnostic to identify your exact water source issues and match the right filter combination โ free for subscribers.
No spam. Unsubscribe anytime.
๐ Related guides you might find useful
How RO Systems Work โ A Complete Guide
Everything about reverse osmosis โ stages, membrane types, TDS reduction, remineralisation, and the best AU systems for 2026.
Coming soon
Bore Water Treatment for Australian Homes
Iron, manganese, hardness, and bacteria in bore water โ what test you need, and what filters actually fix the problem.
Coming soon
Best Water Filters for Caravans & Off-Grid
Compact, low-pressure, and dual-source filter solutions for caravan, camper, and off-grid living across Australia.
Coming soon
Carbon Block vs GAC Filters Explained
The difference between carbon block and granular activated carbon, which removes more chlorine, and when to use each in your filter train.
Coming soon
