Why Does My Toilet Keep Running?

If you’ve ever walked into your bathroom to hear the sound of water running from the toilet long after it’s been flushed, you’ve probably wondered, “Why does my toilet keep running?” While it may seem like a simple problem, a running toilet can lead to unnecessary water waste and higher water bills if left unresolved.

1. The Flush Valve Washer Needs Replacement

One of the most common culprits of a running toilet is a worn-out or damaged flush valve washer. The flush valve washer is located in the toilet cistern and is responsible for sealing the opening between the bottom of the cistern and the bowl when you’re not flushing. If the washer becomes worn, cracked, or simply dirty over time, it can prevent the tank from sealing properly.

When the flush valve washer doesn’t create a proper seal, water will continually leak into the toilet bowl, which causes the toilet to keep running. You might not even notice the slow trickle of water leaking, but it’s enough to make the tank refill itself repeatedly, leading to that familiar running sound. This can be easily checked with placing a few pieces of toilet paper at the back of the toilet bowl and watch to see if the toilet paper starts to get wet, this will indicate water is slowly leaking through from the cistern to the toilet bowl.

Replacing the flush valve washer is a relatively simple fix that requires turning off the water supply to the toilet, draining the cistern, removing the flush valve and swapping out the old washer with a new one. If you’re unsure or if it feels like the flush valve is going to break on removal it might be best to give a plumber a call.

2. Debris Blocking the Flush Valve Washer

Even if your flush valve washer is relatively new, debris like minerals, dirt, or small bits of rubber can accumulate over time and get stuck in the washer or its seat. This can prevent the washer from making a proper seal, leading to the same running toilet problem.

Often, mineral buildup from hard water can cause this type of debris to form. The debris gets in the way of the washer, preventing it from properly sealing and shutting off the water flow into the bowl.

Try cleaning the area around the flush valve seat and washer with a soft brush to remove any debris or buildup. If the debris is too stubborn, you may need to disassemble the flush valve mechanism and soak it in a vinegar solution to dissolve any mineral deposits.

3. The Ballcock Has Failed

The ballcock is another important part of your toilet’s water control system. Located inside the toilet cistern, the ballcock is responsible for regulating the flow of water into the cistern after a flush. It is typically connected to a float arm or float cup, which rises as the water level in the cistern rises. Once the float arm or cup reaches a certain level, it signals the ballcock to stop the water flow.

If the ballcock fails, it can cause the toilet cistern to overfill or keep filling even when it doesn’t need to. A faulty ballcock might also allow water to seep into the cistern without ever shutting off, which results in that annoying running sound.

If you suspect that the ballcock is malfunctioning, it’s usually best to replace it. Ballcocks are relatively inexpensive and can be replaced fairly quickly for standard toilets.

4. Debris in the Ballcock Mechanism

Just like the flush valve washer, the ballcock mechanism is susceptible to debris and mineral buildup. If small particles or mineral deposits get stuck inside the ballcock, it can cause the valve to fail to shut off properly. In some cases, debris may even get lodged in the rubber washer of the ballcock, preventing it from forming a proper seal and causing the cistern to continuously fill.

To address this, turn off the water supply to the toilet and remove the ballcock to inspect it for debris or mineral buildup. If you find any, clean it out gently, or soak the parts in a vinegar solution to break down any tough deposits. If the ballcock appears to be damaged or doesn’t seem to be working properly after cleaning, it may need to be replaced.

5. Old or Incorrectly Set Float

The float is responsible for signalling the ballcock to stop filling the cistern once it reaches a certain water level. If the float is set too high or is damaged, the toilet cistern may keep filling with water beyond the necessary level, causing a constant flow of water into the toilet bowl.

Adjust the float arm so that the water shuts off at the right level. If the float is damaged or not functioning properly, it may need to be replaced. Modern toilets often use a plastic float ball/cup or a cylinder float, all of which are relatively easy to adjust or replace.

To prevent this issue from becoming a recurring problem, here are a few tips:

  • Regularly inspect your toilet’s components (flush valve, ballcock, float, etc.) for wear and tear or buildup.
  • Consider installing a water softener if you live in an area with hard water. This can reduce the risk of mineral buildup in your toilet and other plumbing fixtures.
  • Replace old parts when necessary to maintain optimal function.

Conclusion

A running toilet can waste a lot of water and lead to increased water bills. The primary reasons for a toilet that keeps running are typically related to issues with the flush valve washer or the ballcock mechanism. Whether it’s a worn-out washer, debris blocking the valve, or a faulty ballcock, identifying the root cause and fixing it quickly will save you money and frustration.