A puddle around the base of your toilet is never a welcome sight, but it's a surprisingly common problem in NZ homes — old and new alike. The good news is that the cause is usually straightforward, and depending on your confidence level, some of the fix may be within reach of a capable DIYer. Here's what you need to know.
What Causes a Toilet to Leak at the Base?
Before you grab a mop and call it a day, it's worth identifying exactly where the water is coming from. There are a few common culprits:
- Worn or failed wax ring (pan seal): The most frequent cause. The wax ring (sometimes called a pan seal or closet gasket) sits between the base of the toilet pan and the floor flange, creating a watertight seal. Over time — or if the toilet rocks — this seal can break down and allow water and sewage to seep out.
- Loose toilet pan: If the toilet moves when you sit on it, the fixing bolts may have worked loose, breaking the seal below.
- Cracked toilet base: Less common, but a hairline crack in the porcelain can allow water to escape.
- Condensation: In humid conditions, moisture can collect on the outside of the pan and drip to the floor — this isn't a leak from the plumbing itself.
- Loose or damaged pan collar: The pan collar (floor flange) connects the toilet to the drainpipe. If it's cracked or sitting at the wrong height, it can cause ongoing leaks.
How to Tell Where the Leak Is Coming From
Dry the area thoroughly with old towels, then flush the toilet and watch carefully. If water appears immediately at the base during or after flushing, it's almost certainly the wax ring or pan collar. If the water appears slowly between flushes, check for condensation or a crack in the porcelain. You can also add a few drops of food colouring to the cistern — if coloured water appears at the base, you've confirmed the seal is the issue.
What Can a Homeowner Do?
In New Zealand, drain-related plumbing work is classified as restricted work under the Plumbers, Gasfitters, and Drainlayers Act 2006. This means that work on the drainpipe itself — including the pan collar and any pipework below the floor — must be carried out by a licensed tradesperson registered with the Plumbers Gasfitters & Drainlayers Board (PGDB).
However, a homeowner may legally:
- Remove and refit a toilet pan (the fixture itself), provided no work is done on the drain or waste pipes
- Tighten loose fixing bolts
- Replace a wax ring/pan seal when refitting the pan
If you're comfortable with basic DIY and the pan collar is intact and undamaged, replacing the wax ring yourself is a reasonable task. If there's any doubt about the condition of the drain or collar, stop and call a licensed plumber.
Step-by-Step: Replacing a Toilet Pan Seal (Wax Ring)
What you'll need
- Adjustable spanner and screwdrivers
- Replacement wax ring or pan seal (available at Bunnings or Mitre 10)
- Rubber gloves, old towels, and a bucket
- Putty knife or scraper
- Silicone sealant (optional — see note below)
Steps
- Turn off the water supply at the isolating valve behind or beside the toilet, then flush to empty the cistern.
- Disconnect the water supply hose from the cistern. Have a towel ready for drips.
- Remove remaining water from the pan using a sponge and bucket.
- Unscrew the fixing bolts at the base of the pan. These are usually covered by plastic caps.
- Lift the toilet pan straight up and set it aside on old newspaper or cardboard.
- Scrape away the old wax ring from both the floor flange and the base of the pan. Clean both surfaces thoroughly.
- Inspect the pan collar/floor flange for cracks or damage. If it's damaged, stop here and call a licensed plumber — this is restricted work.
- Press the new wax ring onto the base of the toilet pan (wax side facing down) or set it over the floor flange.
- Lower the pan carefully onto the flange, aligning the bolt holes, and press down firmly with your body weight to compress the wax.
- Refit and tighten the bolts — snug, but don't overtighten or you risk cracking the porcelain.
- Reconnect the water supply, turn it back on, and flush several times. Check carefully for any leaks.
Note on silicone at the base: Some people run a bead of silicone around the outside of the pan base. This can actually trap a future leak inside, hiding it until serious damage is done. It's generally better to leave the base unsealed so any future leak is visible.
When to Call a Professional
Call a licensed plumber if:
- The pan collar or floor flange is cracked or damaged
- The drainpipe itself needs adjustment or repair
- You notice soft or damaged flooring around the toilet (possible water damage or rot)
- The toilet continues to leak after you've replaced the wax ring
- You're not confident working with plumbing fixtures
Unlicensed drain work is illegal in NZ and can void your home insurance. It can also create serious health hazards — sewage leaks carry harmful bacteria and can cause significant structural damage if left unaddressed. BRANZ research highlights how moisture damage from undetected leaks can compromise building elements over time.
You can find qualified, local plumbers in your area through tradedirectory.co.nz.
Comparing Your Options
| Situation | DIY Possible? | Call a Plumber? |
|---|---|---|
| Tighten loose pan bolts | Yes | Not usually |
| Replace wax ring (collar intact) | Yes, with care | Optional |
| Cracked pan collar or flange | No | Yes — restricted work |
| Damaged drainpipe | No | Yes — restricted work |
| Cracked toilet pan | No (replace pan) | Recommended |
| Soft/damaged subfloor | No | Yes |