Yes — replacing an o-ring on a kitchen tap is one of the few plumbing tasks a NZ homeowner can legally do themselves. A leak at the base of the spout (rather than from the pipes under the sink) is almost always caused by a worn or perished o-ring, and with the right tools and a bit of patience, you can fix it in under an hour without needing a licensed tradesperson.
Why Does Water Leak from the Base of a Tap?
Most modern kitchen taps have one or more rubber o-rings — small circular seals — that sit around the body of the spout where it meets the tap body. Over time, these rings dry out, crack, or flatten, allowing water to seep out around the base whenever the tap is in use. This is different from a dripping spout (which usually means worn washers or cartridges) and different again from a leak under the sink (which may involve restricted plumbing work).
Is This Legal for a Homeowner to Do?
Under New Zealand law, replacing tap o-rings and washers is not restricted plumbing work, so you don't need to be licensed to do it. Restricted work — such as connecting or altering water supply pipework, installing sanitary fixtures, or working on hot water systems — must be carried out by a licensed plumber registered with the Plumbers, Gasfitters and Drainlayers Board. Swapping an o-ring on an existing tap falls well outside that definition, so you're good to go.
Tools and Materials You'll Need
- Adjustable spanner or basin wrench
- Flathead and Phillips screwdrivers
- Needle-nose pliers
- O-ring pick or small hook tool
- Silicone grease (plumber's grease)
- Replacement o-rings (bring the old one to the hardware store to match the size)
- Cloth or small towel
- Bucket
Replacement o-rings are inexpensive and widely available at Bunnings or Mitre 10. Buy a small assorted pack if you're unsure of the exact size — they're cheap and it's handy to have spares.
Step-by-Step: Replacing the O-Ring
1. Turn Off the Water Supply
Locate the isolation valves under the sink (usually small inline valves on the hot and cold supply lines) and turn them clockwise to close. If there are no isolation valves, you'll need to turn off the water at the toby (main stopcock), typically near the boundary or in the meter box outside. Open the tap to release any remaining pressure and drain the lines.
2. Remove the Tap Spout
The method varies by tap brand and style. On most mixer taps:
- Look for a decorative cap or grub screw at the base of the spout — remove it with a screwdriver or Allen key.
- Lift or rotate the spout to slide it off the tap body. Some spouts twist off; others pull straight up.
- If it's stiff, wiggle gently — don't force it or you risk cracking the body.
3. Locate and Remove the Old O-Ring
You'll see one or more rubber o-rings sitting in grooves around the tap body. Use your o-ring pick or a small flathead screwdriver to carefully roll them out of their grooves. Inspect them — if they're flattened, cracked, or feel hard and brittle, they're the culprit.
4. Fit the New O-Ring
Match the new o-ring to the old one in diameter and thickness. Lightly coat the new o-ring in silicone grease (not petroleum-based products like Vaseline, which degrade rubber) before fitting. Roll it carefully into the groove, making sure it sits evenly without twisting.
5. Reassemble and Test
Slide the spout back onto the tap body, refit any screws or caps, then slowly reopen the isolation valves. Turn the tap on and off a few times and check the base carefully for any sign of weeping. Dry the area first with a cloth so you can spot even a small drip.
Tips for Success
- Take photos before you disassemble anything — it makes reassembly much easier.
- If you can't identify the tap brand, take the old o-ring and any removed parts to the hardware store for help matching them.
- Popular NZ tap brands include Methven, Dorf, and Caroma — some have brand-specific parts, so check the manufacturer's website or packaging if in doubt.
- If the tap body itself is cracked or corroded, an o-ring won't fix the leak and you'll likely need a full tap replacement.
A Note on Hot Water Systems
If your kitchen tap is connected to a continuous flow (instantaneous) hot water system or a wetback, be aware that any work on the hot water supply pipework is restricted. The MBIE Building Performance website has clear guidance on what homeowners can and can't do. When in doubt, call a licensed plumber.
When to Call a Professional
Call a licensed plumber if:
- The leak is coming from the supply pipes under the sink, not the tap body itself.
- You've replaced the o-ring and the leak persists — the tap may need a new cartridge or full replacement.
- The tap body is cracked or the thread is damaged.
- You're not comfortable turning off the water supply or disassembling the tap.
- Any work involves altering or connecting to water supply pipework.
A qualified local plumber can diagnose and fix the problem quickly and ensure the work meets the NZ Building Code. You can find licensed plumbers in your area on tradedirectory.co.nz.
Safety Note
Always ensure the water supply is fully isolated before starting work. Keep a bucket handy for residual water in the lines. If you're unsure at any stage, stop and seek professional advice — a small leak left unattended can cause significant water damage over time.
Master Plumbers
