How to Fix a Leaking Toilet Cistern (UK)
Locate and fix a leaking cistern: overflow, inlet, doughnut seal, cracked pan or feed pipe.
FluidmasterGeberitRocaWirquin
Systematic diagnosis
Dry every joint with kitchen roll. Isolate the cold. Flush and refill manually with a jug. Look and listen for where the leak reappears — inlet, overflow, doughnut, or cracked ceramic.
Fixes by location
- Overflow pipe drips outside — fill valve set too high or flush valve seal weeping.
- Feed nut drips — new fibre washer.
- Base of pan wet — doughnut seal.
- Pan wet on side — cracked ceramic (replace pan).
Frequently asked questions
- Can I use silicone to seal a leaking cistern?
- Never on internal seals. Silicone on the doughnut just traps the leak until it fails worse.
Shop the spares
Browse toilet & cistern — 6,230 live parts.
View Toilet & Cistern