When you're home alone and you hear the toilet flush, your first thought may be that you either have a ghost or a serial killer making themselves at home in your abode. However, there's no need to call an exorcist or the police. Chances are good your toilet is flushing by itself for a perfectly normal reason. Here's what you need to know to diagnose and fix the issue.
The Flapper is Leaking
A toilet that flushes by itself is almost always the result of a leak in the tank, and usually the cause of that leak is a damaged flapper. The flapper is what stops water from going into the toilet bowl between flushes. If the part is cracked, warped, or not sitting right in the tank, it can cause water to leak into the bowl.
Your toilet bowl is designed to automatically flush when it gets too full (to prevent overflows), so when the leak causes the water in the bowl to reach the max fill point, the toilet empties itself. This can give the impression you have a ghostly guest relieving themselves.
You can confirm whether this is the case by dropping a little bit of food color in the toilet tank. If the water in the toilet bowl changes color after a few hours even though you didn't flush it, your tank is leaking. In many cases, the toilet will also sound like it's constantly running and the water may appear to be moving in the bowl.
Fixing the Problem
This type of problem is pretty easy to fix. The first thing you should do is check that the flapper is sitting correctly. Over time, the flapper may not completely cover the hole between the tank and the toilet because the chain loosened (allowing it to float out of alignment) or the float arm has become maladjusted so the float sits higher than it should. Make sure the chain is tight. If that looks okay, adjust the float arm screw to lower the float back to where it should be.
If those parts appear to be operating just fine, then your next step is to replace the flapper. This is an easy fix that can be done within a few minutes. Turn off the water to the tank, flush the toilet to empty the water from the tank, and then replace the old flapper with a new one you can purchase at your local home improvement store. Turn the water supply back on and do a couple of test flushes to ensure you installed the new flapper correctly and the leaking has stopped.
For assistance with making this repair or help with other plumbing issues, contact a local plumbing service.