A running toilet can waste hundreds of gallons a day without you noticing. Here are the usual culprits, a simple dye test, and the signs a replacement makes more sense.
That faint hiss from the bathroom, or the tank refilling on its own in the middle of the night, is more than an annoyance. According to the EPA’s WaterSense program, a leaky toilet can waste around 200 gallons of water a day. The good news: the cause is usually a cheap part.
The usual suspects
A worn flapper
The rubber flapper at the bottom of the tank seals the water in. Over time it warps, hardens or collects mineral buildup and water slowly seeps into the bowl. In-tank bleach or cleaning tablets can speed this up. This is the most common cause by far.
The fill valve is set too high
If the water level in the tank rises above the top of the overflow tube, it constantly spills down into the bowl and the fill valve keeps topping it up. Adjusting the float usually fixes it; if the valve itself is worn, it gets replaced.
The chain is the wrong length
Too short and it holds the flapper slightly open. Too long and it can get trapped under the flapper. Both keep the toilet running.
Try the dye test
When a new toilet makes more sense
- Cracks in the tank or bowl. Porcelain cracks do not get better and can fail suddenly.
- It rocks or leaks at the base. Often this is just a failed wax ring we can reset, but if the flange or floor is damaged we will tell you.
- Constant clogs. Some older low-flow designs simply do not clear well.
- It is an older high-volume model. Current federal standards allow 1.6 gallons per flush, and WaterSense models use 1.28 or less — an older 3.5-gallon toilet uses far more.
Most running-toilet repairs take well under an hour. If you have a few other small jobs around the house, add them to the same visit and save yourself a second trip charge.