Ceramic disc taps don't actually use a traditional rubber washer — instead, they rely on a ceramic disc cartridge that controls water flow. The good news is that replacing a faulty cartridge is a straightforward DIY job for most homeowners, as long as you can identify the right replacement part and follow a few simple steps.
Understanding Ceramic Disc Taps vs Traditional Taps
Older-style taps use a rubber washer that compresses against a seat to stop water flow. Ceramic disc taps use two precision-ground ceramic discs that rotate against each other. When the discs wear, crack, or become gritty, the tap drips or becomes stiff to operate. The fix is to replace the ceramic cartridge (the self-contained unit housing the discs), not a simple rubber washer.
This is important to understand before you head to the hardware store — asking for a "washer" for a ceramic tap will get you the wrong part.
Tools and Materials You'll Need
- Adjustable spanner or basin wrench
- Flathead and Phillips screwdrivers
- Replacement ceramic cartridge (matching your tap brand and model)
- Silicone grease (plumber's grease)
- Cloth or towel
- Bucket or small container
Finding the right cartridge is the most critical step. Take a photo of your tap, note the brand if visible, and if possible remove the old cartridge first and take it to your local Mitre 10 or Bunnings to match it. Many NZ plumbing suppliers and trade counters at PlaceMakers also stock a wide range of cartridges.
Step-by-Step: Replacing a Ceramic Disc Cartridge
1. Turn Off the Water Supply
Locate the isolating valve under the sink or basin and turn it clockwise to shut off the water to that tap. If there's no isolating valve, you'll need to turn off the water at the toby (main stopcock), usually located near the boundary of your property. Turn on the tap to release any remaining pressure and drain the line.
2. Remove the Tap Handle
Prise off the decorative index cap on top of the handle (hot or cold indicator) using a flathead screwdriver. Underneath you'll find a screw — usually Phillips head. Remove it and lift the handle straight off.
3. Remove the Cartridge
You'll see a cartridge retaining nut or shroud. Unscrew this using your adjustable spanner — turn anti-clockwise. Be careful not to overtighten when reassembling. Once the nut is off, the ceramic cartridge should lift or pull straight out. Note the orientation before removing it.
4. Inspect and Replace
Examine the old cartridge for cracks, chips, or grit damage to the ceramic discs. Even if damage isn't obvious, if the tap has been dripping or stiff, replacement is the right call. Apply a small amount of silicone (plumber's) grease to the O-rings and seating area of the new cartridge before inserting it.
5. Reassemble and Test
Insert the new cartridge in the same orientation as the old one. Refit the retaining nut — hand-tight plus a quarter turn with the spanner is usually sufficient; over-tightening can crack the cartridge. Reattach the handle, replace the screw, and press the index cap back on. Slowly turn the water supply back on and test the tap for leaks and smooth operation.
Important NZ Regulatory Notes
In New Zealand, basic tap maintenance such as replacing a cartridge or washer is generally considered owner-maintenance work and does not require a licensed plumber. However, any work that involves modifying pipework, installing new fittings, or connecting to the water supply is restricted work under the Plumbers, Gasfitters, and Drainlayers Act 2006, and must be carried out by a licensed tradesperson registered with the Plumbers, Gasfitters and Drainlayers Board (PGDB).
If you're unsure whether your job crosses into restricted work, check with the PGDB or consult MBIE Building Performance for guidance on the Building Code and what work requires consent or licensed tradespeople.
For rental properties, landlords should also be aware of Healthy Homes Standards obligations — working taps and adequate drainage are part of your responsibilities. See Tenancy Services for details.
Tips for Success
- Match the cartridge carefully — hot and cold cartridges are often different (they open in opposite directions). Check before ordering.
- If your tap is a mixer tap, there may be a single cartridge controlling both temperature and flow, or two separate cartridges.
- Older or less common tap brands may have cartridges that are hard to source. In that case, replacing the entire tap may be more practical.
- If your water pressure is very high (above the maximum pressure recommended for your fittings (check with your plumber or the fitting manufacturer for guidance)), ceramic cartridges can wear faster. BRANZ has useful guidance on acceptable water pressure in NZ homes.
When to Call a Professional
Call a licensed plumber if:
- You can't identify or source the correct replacement cartridge
- The tap body or seat is damaged or corroded
- There is leaking from the pipework itself, not just the tap
- You need to install an isolating valve (this is restricted work)
- You're not confident working with your home's water supply
- The tap is more than 20–25 years old and may need full replacement
A qualified local plumber can have the job done quickly and ensure everything is up to code. You can find licensed plumbers in your area at tradedirectory.co.nz.
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