One of the most common plumbing issues that homeowners face is a running toilet. But what causes a toilet to run?
If your toilet is constantly running, it usually means water is entering the tank and running out into the bowl when it shouldn’t be. A toilet is designed to fill, flush, and stop. If it keeps refilling or cycling on and off, one of the components inside the tank has likely failed, shifted out of place, or is no longer sealing properly.
Six Reasons Your Toilet is Running
The good news is that the cause of a running toilet usually comes down to a few common issues. Most running toilets are caused by a few common parts inside the tank that control how water moves through the toilet. Further good news is that these components are very inexpensive.
A Worn or Misaligned Flapper
One of the most common causes of a toilet running continuously is a worn-out flapper. The flapper is a rubber flap that acts as a valve at the bottom of the tank. It opens when you flush, and closes once the water in the tank drains. When the flapper closes, the tank will retain water until the next time it is flushed.
Over time, the rubber might become stiffer, deformed, misaligned, or develop tiny gaps that will not allow it to close tightly. When this occurs, water may slowly leak out of the tank into the bowl. As the water level drops, the tank refills. This creates an endless cycle of the toilet filling with water and running. In some cases, the flapper is not worn; it just does not sit correctly. If there is debris on the sealing surface or mineral deposits build up around the flapper (or if the flapper is not centered), water will be able to leak around the flapper.
A Faulty Fill Valve
Another reason a toilet keeps running is a faulty fill valve. The fill valve is responsible for controlling the flow of water into the tank after each flush. Once the tank reaches the right level, the fill valve will completely shut off the flow of water into the tank.
If your fill valve begins to wear out, it may not completely close. As a result, water will continue to flow into the tank even when it’s full. The extra water flows into the overflow tube and down into the bowl, preventing the tank from shutting off properly and causing the toilet to keep refilling. Fill valves will wear out over time, especially in homes that have hard water, because of the build-up of mineral deposits on their moving parts.
The Water Level Is Set Too High
To prevent overfilling of the toilet tank, all toilets are equipped with an overflow tube. If the water level in the tank exceeds the proper height, any excess will flow through the overflow tube and into the toilet’s bowl. When that happens, the tank will continue to refill due to the water leaving through this route. In most cases, the problem is caused by the float adjustment being set too high.
If the float fails to stop the tank from filling to the designed height, the overflow tube will continuously drain water, causing the tank to never fill completely. This is an easily adjustable component, which typically requires no replacement parts.
A Flapper Chain That Is Too Tight or Tangled
The chain connecting the flush lever to the flapper can also affect how the toilet functions. If too much tension is on the chain, then the flapper may not close completely after the flush is complete. Even a small gap can allow water to leak from the tank.
Chains can also get caught or tangled beneath the flapper, which will prevent it from sealing correctly. If this happens, water will continue to leak from the tank and continue to fill the toilet.
Because the leak is typically so slow, most homeowners won’t even know their toilet is running until they check it periodically throughout the day.
Mineral Buildup Inside the Tank
In areas with hard water, minerals build up inside toilet tanks and can interfere with the movement of various valves, seals, and other moving parts. Hard water is typical when your water is being supplied from a well, not a reservoir.
Build-up of minerals over time can lead to a toilet flapper not closing completely, or the fill valve can become stuck in the open position. If the moving parts are unable to move properly, the toilet will either continually fill or refill by itself.
Most often, this kind of buildup occurs over a long period of time, so many homeowners may not notice that their toilets are getting worse until they have been using them for some time.
Aging or Worn Internal Parts
Toilets can last for many years, but the internal parts inside the tank wear out over time. Over time, rubber seals will deteriorate, plastic components become brittle, and valves lose their precision due to everyday use.
When multiple different components begin to wear out simultaneously, this is often when a toilet will run intermittently or continue to fill after being flushed. Older toilets may have many minor issues that, when they occur together, will cause the toilet to run constantly.
If your toilet is running consistently, it’s probably because most of its internal parts have reached the end of their life cycle. If multiple components are worn, it may be best to simply replace the entire toilet.
Why a Running Toilet Shouldn’t Be Ignored
A running toilet may seem like a minor annoyance; however, a running toilet usually indicates that you have a problem with the flow of water that should not be happening. Even just a small leak will waste thousands of gallons of water yearly. By wasting this much water, your water bill will typically reflect this cost over time. Read our blog post: How Much Can A Running Toilet Increase Your Water Bill
Sewer costs in many cities are based upon water consumption; therefore, in many metropolitan areas, a running toilet could also cost you significantly more than a normal water bill. Additionally, what seems like a small plumbing problem can potentially cost you a great deal of money.
Final Thoughts
If you’ve been asking yourself why your toilet keeps running, the answer usually comes down to a worn flapper, a faulty fill valve, an incorrect water level, or aging parts inside the tank. These components control how water moves through the toilet, and when one of them stops working properly, the toilet continues to refill.
A toilet should fill, flush, and stop. When it doesn’t, it’s a sign that water is being wasted and the system needs attention.
