What is the most common cause of a running toilet leak?

The most common cause of a running toilet is a worn or misaligned flapper. A faulty fill valve or float can also keep water flowing. Technicians can replace these parts during service or install a new toilet if needed. Eco-friendly, rebate-eligible options are available when replacing.

Quick checks:

• Put a few drops of food coloring in the tank; color in the bowl without flushing means a leak.
• Check the flapper for wear or chain slack.
• Listen for hissing from the fill valve.

Updated: 2025-12-21

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