How to Fix a Leaking Toilet

Toilet leaks are one of the most common household plumbing problems — and one of the most wasteful. A running toilet can waste 200 gallons of water per day. Here's how to diagnose and fix every type of toilet leak.

Step 1: Identify Where It's Leaking

Water on the floor around the base — failed wax ring or loose floor bolts
Water running into the bowl constantly — worn flapper or faulty fill valve
Water leaking from the tank — cracked tank, loose tank bolts, or failed tank-to-bowl gasket
Water between tank and bowl — failed spud washer or loose tank bolts
Water supply line leaking — loose connection at the wall or tank

Fix 1: Toilet Running Constantly (Flapper or Fill Valve)

This is the most common toilet leak. Lift the tank lid and look:

If the flapper isn't sealing: Water trickles into the bowl continuously. The flapper is worn or warped.

👉 Universal toilet flapper — turn off the water supply, flush to empty the tank, unhook the old flapper from the overflow tube ears and disconnect the chain, snap on the new flapper and reconnect the chain (leave 1/2 inch of slack)

If the fill valve won't shut off: Water keeps running into the tank and overflows into the bowl through the overflow tube.

👉 Fill valve and flapper repair kit — replace both at once for a complete fix. Turn off water, flush, disconnect the supply line, unscrew the old fill valve locknut, install new valve, reconnect supply line.

Fix 2: Leaking at the Base

Water pooling around the base means the wax ring seal has failed or the toilet is loose.

Check if the toilet rocks — tighten the floor bolts (plastic caps at the base) first. Sometimes this alone stops the leak.
If the toilet still leaks, the wax ring needs replacement:
👉 Wax-free toilet installation kit — turn off water, flush, disconnect supply line, remove floor bolts, lift the toilet straight up, scrape off old wax, install new seal, reset toilet, reconnect.

Fix 3: Leaking from the Tank

Loose tank bolts: Tighten the bolts inside the tank (rubber washers compress to seal). Don't overtighten — you can crack the porcelain.

Failed tank-to-bowl gasket: The large rubber gasket between the tank and bowl has deteriorated. Drain the tank, remove it from the bowl, replace the gasket, and reinstall.

Fix 4: Supply Line Leak

Tighten the connection at the shut-off valve and at the tank bottom
If still leaking, replace the supply line — they're inexpensive and easy to swap
Wrap threads with PTFE tape before reconnecting

Bottom Line

Most toilet leaks are fixed by replacing the flapper, fill valve, or wax ring — all inexpensive parts available at any hardware store. Identify where the leak is coming from, turn off the water, and swap the worn part. Most repairs take under an hour.

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