Why Is the Toilet Flushing Itself?

toilet leak to bowl

OK, so you just heard the toilet flush in the middle of the night. No one else is in the house, and you don’t think your home has a ghost. Later that night, you hear it again. Ughhh. How will you explain this to the plumber?

Don’t worry. What you’re probably hearing is the toilet refilling as if it had been flushed. But how is that possible? Water in the tank is slowly leaking past the flush valve and into the bowl. As the bowl fills, the water silently flows down the drain line. When the water in the tank gets low, the automatic fill valve opens and you hear the tank filling – just as if the toilet had been flushed.

The fix is simple: clean or repair the flush ball or flap valve. At times, the problem can be fixed just by wiping deposits off the mating surfaces. Other times you’ll need to replace the valve because of a crack or surface imperfection.

If you want to test for this type of silent leak, place a few drops of food coloring in the tank. Within a short time, you’ll notice the color in the bowl – a sure sign of a leaking flush valve.

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