Which situation matches?
Water enters the overflow
Compare the tank level with the model marking and read the fill-valve instructions. Do not assume the flapper is responsible.
Water stays below the overflow
A food-coloring check can distinguish a tank-to-bowl leak from an external leak.
Water is outside the tank
Stop using the fixture and arrange plumbing help; a cracked tank or leaking connection needs a different response.
Prepare for the next step
Flashlight, towel, food coloring and the toilet model instructions. Set the tank lid on a padded, stable surface.
Record when the symptom began, what changed and which observations you can make safely. Do not dismantle equipment simply to provide a more detailed description.
Follow the full guide
The full guide explains the safe procedure, mistakes to avoid, professional stopping points and prevention. Browse supporting publisher tutorials, or use the moderated Q&A for a non-urgent question.
Sources and limits
Documentation checked November 4, 2026. AI-assisted educational content; no property inspection or licensed professional review is claimed.