How to Fix a Running Toilet

A running toilet is almost always a bad flapper, a stuck fill valve, or a chain that's too tight — all under-$20 fixes.

Common causes

• Warped or worn flapper not sealing the flush valve
• Fill valve stuck open or set too high
• Flush chain too short and holding the flapper up
• Cracked overflow tube

Step-by-step

1. 01Lift the tank lid and watch a full flush cycle
2. 02Push down on the flapper — if the run stops, replace the flapper
3. 03Check the water level — it should sit ~1 inch below the overflow tube
4. 04Adjust the float or replace the fill valve if the level won't hold

When to call Northbridge

• Water is leaking onto the floor, not just running in the tank
• The tank has a visible crack
• You've replaced the flapper and it still runs