Buyer guide · Updated 22 Oct 2026 · By the Filtsap technical team

Spun vs wound vs pleated filter cartridge: which should you choose?

Short answerChoose a PP spun (melt-blown) cartridge for low-cost water pre-filtration, a string wound cartridge for higher flow, pressure, oils and viscous liquids, and a pleated cartridge for fine (0.22–10 µm), low-pressure-drop polishing. Spun and wound cartridges are depth filters. Pleated cartridges are surface filters with a much larger area.

Quick comparison

	PP spun / melt-blown	String wound	Pleated
Filtration type	Depth (graded density)	Depth (diamond winding)	Surface (large area)
Typical micron	1–50 µm	1–100 µm	0.22–40 µm
Cost per piece	Lowest	Low–medium	Higher
Flow / pressure	Medium	High	Highest flow, lowest ΔP
Viscous liquids / oil	Fair	Excellent	Good (coarser grades)
Best for	RO pre-filter, process water	Oils, beverages, chemicals	Final polishing, pharma

PP spun (melt-blown)

Made by blowing molten polypropylene into microfibres. It is cheap, binder-free and consistent, which is why it is the world's most common water pre-filter. See PP spun cartridges →

String wound

PP yarn is wound on a rigid core in a diamond pattern. It is stronger, handles more pressure and viscous fluids, and is available in carbon-impregnated form. See wound cartridges →

Pleated

A thin media is folded into dozens of pleats, giving 3–5 times the surface area. This means low pressure drop, high flow and fine absolute ratings. See pleated cartridges →

A common combination

Many plants use all three: a wound cartridge (25 µm), then spun (5 µm), then pleated (1 or 0.45 µm). This gives the lowest cost per litre with the finest outlet quality.

FAQs

Can I put a pleated cartridge in my existing housing?

Yes, if the length and end type match (for example a 20" DOE cartridge with 62–70 mm OD). Send us your housing details to confirm.