Symptoms
- Toilet runs constantly (chain too short, holding flapper open)
- Weak flush or won't flush at all (chain too long or tangled)
- Chain visibly looped around the flapper or lift arm
- Flapper doesn't return flat after flushing
Likely causes
- CommonChain too shortA short chain holds the flapper slightly open, causing constant running.
- CommonChain too long or tangledExtra slack can let the chain wrap around the flapper hinge, preventing a full lift or a full seal.
- PossibleWrong chain attachment point on the handle armUsing the wrong hole on the arm changes the effective chain length and flush action.
What to do
- Remove the tank lid and observe the chain's slack; it should have about half an inch of give when the flapper is closed.
- Unhook the chain and remove any tangles or kinks along its length.
- Reattach it using a hole on the handle arm that gives the right slack, trimming excess links if the chain is too long.
- Avoid leaving so much slack that the chain can fall to the side and get caught under the flapper.
- Flush several times to confirm the flapper lifts fully and reseats flat each time.
Tools and parts
- Pliers (to remove excess chain links)
When to call a pro
This is a DIY-only repair and doesn't typically require a plumber.
Safety
Generally low risk
Generally low risk for a careful person. Stop if anything looks different from what this guide describes.