Toilet tank bolts usually leak because their rubber sealing washers are perished, compressed or displaced. Loose or corroded hardware, uneven tension, a failed tank-to-pan gasket or cracked porcelain can cause similar water tracking. Stop using the toilet if the leak is uncontrolled and check how urgently a leaking toilet needs attention.
Confirm where the water is escaping
Dry the underside of the cistern, then hold dry tissue around each fixing while it refills. The first wet point helps identify the likely source:
- Water centred on a fixing bolt: The bolt washer or fixing is likely leaking.
- Water centred on the large tank-to-bowl connection: The main gasket may have failed instead.
- Water tracking from the side: Check whether the toilet supply line or isolation valve is leaking.
Water can travel across porcelain before dripping, so a plumber may need to dry and retest the toilet before dismantling it. Water appearing at floor level can also have a different cause from a cistern fixing leak.
What can you do safely?
Stop using the toilet. If the isolation valve is accessible and turns easily, close it and place towels beneath the cistern. Do not force a seized valve, overtighten the bolts, cut hardware near porcelain or remove an unsupported cistern.
Keep clear and seek urgent professional help if water is spreading towards electrical fittings, wastewater may be escaping or the porcelain is cracked. A damaged cistern or pan can fail suddenly.
How is the leak fixed?
A licensed plumber will isolate and drain the cistern, support it, then inspect the washers, bolts, tank-to-pan gasket and porcelain. Depending on the source, the plumber may replace compatible sealing washers and corroded hardware, renew the main gasket or recommend replacing a cracked component.
The fixings must be tightened gradually and evenly because excessive or uneven pressure can crack porcelain. The plumber will refill and flush-test the toilet, then check each connection for further leakage.
If the fixings are seized, the porcelain is cracked or the leak persists, keep the water off and contact our licensed leaking toilet plumbers for a safe repair. For over 15 years, Sydney homeowners have relied on Fixed Today for meticulous toilet and cistern repairs. When you contact us, our dispatch team asks a couple of screening questions—such as your toilet suite brand, whether the cistern is close-coupled ceramic or concealed behind a wall, and whether the mini-stop valve isolates completely—so our technician arrives stocked with genuine stepped conical washers, stainless bolts, and replacement seals. On site, our licensed plumber walks you through a clear task breakdown to ensure all fixture connections comply with AS/NZS 3500.1 (the national plumbing standard for water services, ensuring watertight connections and safe pressure control), backed by fixed upfront pricing and a $0 call-out fee on approved work.