How to Fix a Toilet That Rocks or Moves at the Base

A toilet that rocks or wobbles at the base is more than just annoying — left unfixed, it can crack the pan, break the seal at the floor, and eventually cause water or sewage leaks beneath your floor. The good news is that in many cases the fix is straightforward, though some steps do involve restricted plumbing work that must be carried out by a licensed tradesperson.

Why Does a Toilet Rock?

Before reaching for the tools, it helps to understand what's causing the movement. Common culprits include:

• Loose or corroded floor bolts (also called closet bolts or pan bolts) — the bolts that secure the toilet pan to the floor or pan collar
• A worn or damaged pan collar — the fitting set into the floor that the toilet connects to
• An uneven or damaged floor — tiles, timber, or concrete that has settled, cracked, or rotted
• A missing or compressed rubber gasket between the pan and the floor
• Improper original installation — the toilet was never properly bedded or secured

A small amount of rocking is sometimes caused by nothing more than a slightly uneven tile. A larger wobble, or one accompanied by a bad smell or damp floor, suggests a failed seal and needs urgent attention.

What You Can and Cannot Do Yourself

In New Zealand, drainlaying and certain plumbing connections are restricted work under the Plumbers, Gasfitters, and Drainlayers Act 2006. Disconnecting and reconnecting a toilet pan from the pan collar (the fitting that connects to the drain) is generally considered restricted plumbing work and must be done by a licensed tradesperson registered with the Plumbers Gasfitters & Drainlayers Board.

What a homeowner can typically do without a licence:

• Tighten accessible floor bolts (if the toilet does not need to be lifted)
• Shim the base to reduce rocking on an uneven floor
• Inspect the area around the base for signs of moisture or damage

If the toilet needs to be lifted off the pan collar to replace the wax ring/gasket or re-seat the collar, call a licensed plumber.

Step 1 — Check and Tighten the Floor Bolts

Most toilet pans are secured by two bolts on either side of the base, covered by plastic caps. Gently prise off the caps with a flat-bladed screwdriver.

• If the nuts are loose, tighten them gradually — alternate sides and go slowly. Over-tightening can crack a ceramic pan.
• If the bolts spin freely or are corroded through, they'll need replacing. This usually means lifting the pan, which is restricted work — contact a licensed plumber.
• Use a spanner or adjustable wrench, not power tools.

Step 2 — Shim the Base

If the bolts are tight but the toilet still rocks slightly on an uneven floor:

1. Identify which side lifts by gently pressing each corner.
2. Slide plastic toilet shims (available at Bunnings or Mitre 10) under the raised side until the toilet sits firmly without rocking.
3. Score off the excess shim with a utility knife once you're happy with the fit.
4. Run a bead of sanitary-grade silicone sealant around the base — but leave a small gap at the back. This allows any future leak to be visible rather than hidden under the sealant.

Note: Do not use silicone to fix a rocking toilet — it will mask movement and can hide a worsening leak.

Step 3 — Inspect for Water Damage

While you have the caps off and are working at floor level, check carefully for:

• Soft or spongy flooring around the toilet base (a sign of water damage or rot)
• Staining or mineral deposits on the floor
• Odour suggesting a broken wax seal or drain leak

If you find any of these, stop and call a licensed plumber. A failed wax ring or cracked pan collar can allow sewage gases and wastewater to enter your subfloor — a serious health and structural risk. The MBIE Building Performance website has useful guidance on what constitutes building defects and when repairs may require consent.

Step 4 — Check the Floor Itself

If the floor around the toilet is damaged, repairs may be needed before the toilet can be properly re-secured. Rotted timber subfloor or cracked tiles will need to be addressed first. Depending on the extent of work, a building consent may be required — always check with your local council. For guidance on consent requirements and Schedule 1 exemptions, visit MBIE Building Performance.

When to Call a Professional

Call a licensed plumber if:

• The toilet needs to be lifted off the floor to access the pan collar or replace the wax ring/gasket
• Floor bolts are corroded, broken, or spinning freely
• There is evidence of a leak, water damage, or sewage smell
• The pan collar itself is cracked or has shifted
• You're unsure about any step in the process

Attempting restricted plumbing work yourself is illegal and can void your home insurance. You can find qualified, local plumbers on tradedirectory.co.nz.

For rental properties, landlords should also be aware of obligations under the Healthy Homes standards — a leaking or unsanitary toilet must be repaired promptly.

Safety Note

Always turn off the water supply to the toilet cistern at the isolating valve (usually on the wall or floor behind the toilet) before doing any work. Flush the toilet to empty the cistern before you begin.

Sources & Further Reading

• Plumbers Gasfitters & Drainlayers Board — find a licensed plumber
• MBIE Building Performance — building consent information
• Tenancy Services — Healthy Homes standards
• WorkSafe NZ — working safely at home
• BRANZ — building and construction guidance