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Sediment Filter Micron Ratings: Which One Do You Need?
- Smaller micron = finer filtering, faster clogging
- Stage coarse → fine on dirty water
- 5 micron is the common RO pre-filter
- Change when pressure drops or on schedule
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What Is a Micron?
One micron is a thousandth of a millimetre. A sediment filter with a 5 micron rating is designed to stop particles around that size and larger, such as sand, silt and rust.
Which Micron for Which Job?
| Rating | Typical use |
|---|---|
| 50 micron | First stage on very sandy or muddy water |
| 20 or 10 micron | General pre-filtering of borehole and tank water |
| 5 micron | The common pre-filter before carbon and RO |
| 1 micron | Final polish before UV so particles do not shade microbes |
Sediment filters remove particles only. They do not remove salts, chemicals or germs; see RO vs UF and UV sterilizers.
Cartridge Size: 10", 20", Slim or Big Blue
Length (10 or 20 inch) and diameter (slim or the wider Big Blue) must match the housing. Bigger cartridges hold more dirt and pass more flow, so they are used for whole-house and commercial systems.
Polypropylene Sediment Filter Cartridges 10″ Big BlueKSh 350
Polypropylene Sediment Filter Cartridges 20″ SlimlineKSh 700
Standard/Slimline Blue Plastic Filter Housings 10″KSh 1,900
Blue Plastic Filter Housings 20″KSh 3,500
Standard/Slimline Clear Plastic Filter HousingsKSh 1,600
H-TECH Filter Cartridge and Replacement Filter RangeKSh 17,400
H-TECH Filter Housing & Bag Filter RangeKSh 1,950Current listed prices incl. VAT (updated 4 October 2026).
When to Change a Sediment Cartridge
- Water flow or pressure after the filter drops.
- The cartridge is visibly brown and packed with dirt.
- On the schedule your installer set (dirty water needs more frequent changes).
Very dirty water ruins cartridges quickly: settle it in a tank first or use a media filter. See bag and disc filters and sand filter backwashing.
Watch: RO purifiers and water ATMs
Frequently asked questions
What does micron rating mean on a water filter?
The particle size the filter is designed to catch; a smaller number is a finer filter.
Is 1 micron or 5 micron better?
1 micron filters finer but clogs faster; 5 micron is the common pre-filter, with 1 micron used before UV when needed.
Which sediment filter is used before RO?
Usually a 5 micron cartridge, after any coarser stages.
How often should I change a sediment filter?
When flow drops or it is visibly clogged; dirty water needs more frequent changes.
Does a sediment filter remove bacteria?
No, it removes particles; use UV, UF or RO for germs.