What Is a Shower Cartridge?

The cartridge is the internal mechanism inside a single-lever or ceramic disc tap that controls water flow and temperature. When a shower tap drips, is hard to turn, or will not shut off fully, the cartridge is usually the problem — not the tap body itself. Replacing the cartridge is far cheaper than replacing the entire tap ($20–80 for a cartridge vs $200+ for a new tap).

Before You Start

Important: Identify your tap brand and model before buying a cartridge. Cartridges are brand and model-specific — a Caroma cartridge will not work in a Methven tap. Remove the old cartridge first, take it to a plumbing supplies store (Reece, Tradelink, Bunnings) and match it or order from the tap manufacturer. In Australia, plumbing work that involves the water supply may require a licensed plumber in some states for certain work — check your state’s plumbing regulations if in doubt.

How to Replace a Shower Cartridge

  1. 1

    Turn off the water supply

    Find the isolation valve for the shower (a small valve on the hot and cold pipes leading to the shower, often in a nearby cupboard or access panel) and turn off. Or turn off at the main water meter. Open the shower tap to release pressure and confirm water is off.

  2. 2

    Remove the tap handle

    Look for a decorative cap on top of or behind the handle — pry it off gently with a flathead screwdriver. Underneath is usually a Phillips or flat-head screw. Remove the screw and pull the handle off. Some handles have a grub screw (Allen key) on the side or base.

  3. 3

    Remove the retaining nut or clip

    With the handle removed, the cartridge is held in place by a nut (use an adjustable spanner) or a retaining clip (pry off with a flathead screwdriver). Note the exact position and orientation of the cartridge before removing — take a photo.

  4. 4

    Pull out the old cartridge

    Grip the cartridge stem and pull straight out. It may require significant force if mineral deposits have built up — wiggle gently as you pull. Bring this cartridge to the plumbing store to match the replacement.

  5. 5

    Insert new cartridge and reassemble

    Insert the new cartridge in the same orientation as the old one (check your photo). Push in firmly until fully seated. Reattach the retaining nut or clip. Reattach the handle and screw. Turn water supply back on and test — check for leaks at the tap body and confirm hot and cold work correctly.

Frequently Asked Questions

Dripping from the spout when the tap is off: cartridge fault. Leaking around the base of the tap handle or body: O-ring failure. O-rings are much cheaper ($2–5 for a set) and easier to replace than the whole cartridge. Open the tap as above and inspect the cartridge body for cracked or flat O-rings before buying a whole new cartridge. If O-rings look intact, replace the cartridge. Many plumbing stores sell cartridge service kits that include both the cartridge and fresh O-rings.
This varies by state. In Victoria, NSW and most Australian states, like-for-like replacement of a tap cartridge is considered maintenance that homeowners can perform themselves. Any work that requires cutting or joining pipes, or altering the plumbing configuration, requires a licensed plumber. If you are replacing the same cartridge in the same tap body without changing any pipework, DIY is generally permissible. When in doubt, check with your state’s plumbing regulator or use a licensed plumber.