Yes, replacing a bath plug and chain waste is something most NZ homeowners can tackle themselves. It doesn't typically involve restricted plumbing work, so no licence is required — as long as you're swapping like-for-like and not altering any pipework beyond the waste fitting itself. That said, it pays to understand exactly what's involved before you start.
What Is a Bath Plug and Chain Waste?
A bath plug and chain waste is the fitting at the bottom of your bath that lets water drain away. It consists of a few key parts:
- The plug – usually rubber or metal, seals the drain hole
- The chain – connects the plug to the overflow or a fixing point
- The waste fitting – the threaded body that sits in the bath's drain hole and connects to the trap below
- The overflow plate – the decorative cover on the bath's overflow hole (often connected to the chain)
When the rubber plug deteriorates, the chain rusts, or the waste body corrodes, it's time for a replacement.
Is It Restricted Plumbing Work in NZ?
Under NZ law, restricted sanitary plumbing work must be carried out by a licensed tradesperson registered with the Plumbers, Gasfitters and Drainlayers Board (PGDB). However, replacing a bath plug and chain waste — where you are simply unscrewing the old waste fitting and screwing in a new one of the same type, without modifying any pipework — is generally considered maintenance work that a homeowner can do themselves.
If you need to alter, extend, or repair the drain pipework or trap beneath the bath, that work is restricted and must be done by a licensed plumber. When in doubt, check with the PGDB or your local council.
What You'll Need
Tools and materials:
- Adjustable spanner or basin wrench
- Flathead screwdriver
- Plumber's putty or silicone sealant (check your bath material first — silicone is safer for acrylic baths)
- Replacement plug and chain waste kit (available at Bunnings or Mitre 10)
- Old towels or a bucket
- Thread tape (PTFE tape)
Tip: Before buying, measure your existing drain hole diameter (most NZ baths use a standard 44 mm or 1¾ inch hole, but check yours first) and take a photo of the old fitting to match it up at the hardware store.
Step-by-Step: Replacing a Bath Plug and Chain Waste
1. Remove the Old Waste
- Place a towel in the bath to protect the surface.
- Unscrew the overflow plate (usually one or two screws) and set it aside.
- Insert a flathead screwdriver into the drain grate slots to hold it steady, then unscrew the waste body from below using a spanner — or use a drain key if you have one.
- Lift out the old waste body, plug, and chain.
2. Clean Up the Drain Hole
- Remove any old putty, sealant, or gunk from around the drain hole and the underside of the bath.
- Check the bath surface for cracks or damage while you're in there.
3. Fit the New Waste
- Apply a thin bead of plumber's putty around the underside flange of the new waste body (for cast iron or steel baths). For acrylic or fibreglass baths, use silicone sealant instead — putty can damage these surfaces.
- Drop the new waste body into the drain hole from above.
- From underneath (or through the access panel if your bath has one), hand-tighten the back nut onto the waste thread, then snug it up with a spanner. Don't overtighten — you can crack an acrylic bath.
- Wrap PTFE tape around any threaded connections to the trap.
4. Attach the Chain and Overflow Plate
- Hook the chain to the plug and connect the other end to the overflow plate bracket or the designated fixing point.
- Screw the overflow plate back into position.
5. Test for Leaks
- Run water into the bath and check underneath for any drips.
- Put the plug in and fill the bath partway, then pull the plug and watch the drain — water should flow freely with no leaks around the waste fitting.
Common Pitfalls to Avoid
| Pitfall | How to Avoid It |
|---|---|
| Wrong size waste fitting | Measure drain hole before buying |
| Using putty on acrylic baths | Use silicone sealant instead |
| Overtightening the back nut | Hand-tight plus a quarter turn is usually enough |
| Forgetting PTFE tape on threads | Always tape threaded connections |
| Not checking the trap below | Inspect for corrosion or blockages while you're there |
When to Call a Professional
Call a licensed plumber if:
- The trap or drain pipework beneath the bath is corroded, cracked, or needs replacing
- You discover the bath drain hole is damaged or non-standard
- Water is leaking from pipework rather than just the waste fitting
- You're not confident working in a confined space under the bath
- The job turns out to be more complex than a straight swap
For restricted plumbing work, always use a tradesperson licensed with the PGDB. You can find qualified local plumbers on tradedirectory.co.nz.
Safety note: Turn off the water supply to the bathroom if there's any risk of accidentally disturbing supply pipes. Keep the work area dry and well lit.
Master Plumbers
