CSLB C-36 Plumbing ContractorService, Repair, and MaintenanceMedium
A client observes a small, intermittent leak around the base of their toilet, especially after flushing. The tank-to-bowl bolts appear tight, and there are no visible cracks in the porcelain. What is the most likely source of the leak?
- AA loose or damaged supply line connection to the fill valve.
- BA faulty wax ring or rubber gasket between the toilet bowl and the floor flange.
- CCondensation forming on the outside of the toilet tank due to high humidity.
- DA worn-out flapper valve seal, allowing water to continuously run into the bowl.
Show answer & explanationAnswer & explanation
Correct answer: B. A faulty wax ring or rubber gasket between the toilet bowl and the floor flange.
A leak around the base of the toilet that occurs after flushing, with no visible cracks and tight tank-to-bowl bolts, almost always points to a compromised seal between the toilet bowl and the floor. The wax ring (or a rubber gasket in some installations) is designed to create this watertight seal and can degrade or shift over time, especially with movement of the toilet.
Why the other options are wrong
- A. A loose supply line connection would cause a leak at the back of the toilet, usually near the fill valve, not specifically at the base after flushing.
- C. Condensation forms on the outside of the tank (or bowl) and would be a continuous drip, not specifically triggered by flushing, and often distinguishable from a leak by its clear, external nature.
- D. A worn flapper valve would cause the toilet to run continuously (fill valve cycling), but the water would go into the bowl and then down the drain, not leak externally from the base.
Toilet Base Leak
Water leaking from underneath the toilet, typically around the floor, often after flushing.
- Indicates a failure of the seal between the toilet and the floor flange.
- Most commonly caused by a degraded or shifted wax ring/gasket.
- Requires removal of the toilet and replacement of the seal.
- Can lead to subfloor damage if not addressed.
Memory trick: The wax ring's sigh, as water goes by.