Water Filters

Filter cartridges are the consumable heart of every treatment system. Two things identify the one you need: the physical size that fits your housing, and the micron rating or medium that suits the job. Get the first wrong and it will not seat; get the second wrong and it either passes what it should hold back or clogs within weeks.

Sizes

Standard cartridges are roughly 2.5 inches in diameter and come in 10, 20, 30 and 40 inch lengths. Big Blue (jumbo) cartridges are around 4.5 inches in diameter, in 10 and 20 inch lengths, and pass far more flow — which is why they are used on building inlets while standard cartridges serve under-sink units.

If you are unsure, take the old cartridge with you or send us a photo of it next to a tape measure. Sending the wrong size back is avoidable in a two-minute message.

Micron rating

A smaller number holds back finer particles. A 1 micron cartridge is finer than a 5 micron, and a 5 finer than a 20. Finer is not automatically better: a very fine cartridge on turbid water clogs quickly and drops pressure. On well water a coarse stage ahead of a fine one — 20 micron then 5, for example — lasts considerably longer than a single fine cartridge.

Types and what each does

• Spun (melt-blown): graded density sediment filtration, the usual first stage.
• String-wound: sediment filtration with higher dirt-holding capacity, suited to well water.
• GAC (granular activated carbon): reduces chlorine, odour and taste.
• CTO (carbon block): like GAC but with finer mechanical filtration as well.
• Washable mesh: reusable coarse screening, cleaned rather than replaced.
• Mineral / post-carbon: final stage after RO, finishing the taste.

When to change them

Sediment cartridges are changed when flow drops noticeably — the honest signal is pressure, not the calendar. Carbon is changed on time, typically every six months, because it stops adsorbing long before it looks used. Cartridges are consumables and are outside warranty cover.