How To Stop Your Toilet Overflowing (Homeowner’s Guide)

Dealing with a flooded bathroom is an ordeal no homeowner wants to face, but knowing how to stop your toilet from overflowing can save you time, money, and prevent potential structural damage to your bathroom. 

We will explore common causes of toilet overflowing and provide step-by-step instructions on how to tackle this prevalent issue with confidence. From faulty fill valves to the art of unclogging a drain, we hope to provide some knowledge every homeowner will find useful. 

Sometimes, an overflowing toilet can become an emergency situation which requires professional assistance. Allphase Restoration toilet overflow services offers comprehensive emergency support within 60 minutes or less. We can help you identify the cause and address any repairs that need to be made on-site. 

Common Causes of Toilet Overflows

toilet fixed after overflowing

Toilet overflows can be caused by a clogged toilet bowl or drain, a faulty fill valve, or a malfunctioning flapper valve.

Clogged Toilet Bowl or Drain

A toilet clog is the single most common reason for a toilet overflowing. It is often the result of flushing too much waste and too much toilet paper at once.

In some cases, the issue stems from using the toilet to dispose of inappropriate materials such as diapers, wipes, and feminine hygiene products that don’t break down in water like toilet paper does. These materials are not septic tank safe. Attempting to flush these sorts of materials often results in a clogged toilet drain.

To prevent this type of clog-induced overflow, it’s essential to ensure that only human waste and a modest amount of standard-issue toilet paper are flushed.

Additionally, installing a small trash bin near the restroom facilities can encourage proper disposal practices for items incompatible with sewer systems or septic tanks.

Faulty Fill Valve

A faulty fill valve can wreak havoc on your toilet’s performance, septic tank, and even lead to overflowing. As one of the most common problems in running toilets, the fill valve is responsible for controlling water flow into the tank after each flush.

To prevent further damage and potential mold growth from excess moisture, it’s essential to check your fill valve regularly for signs of wear. This includes listening for unusual sounds like hissing or whining when the toilet is not in use and observing if there’s a constant trickle of water down the sides of the bowl long after flushing.

If you notice any such issues, consider replacing or adjusting the faulty fill valve with a new one available at hardware stores.

Malfunctioning Flapper Valve

A malfunctioning flapper valve can be a primary cause of toilet overflows, leading to significant water damage and potential health risks related to mold growth. 

The flapper valve is an essential component in the toilet flushing mechanism, as it controls the release of water from the toilet tank into the bowl; when functioning correctly, it prevents excess moisture and water leaks.

For instance, imagine a situation where your older low-flow toilet starts overflowing because its aging flapper valve no longer provides an adequate seal. In such cases, quick DIY solutions include adjusting or replacing the faulty flapper valve––available at most hardware stores––to ensure proper sealing and prevent further damage caused by overflow.

For more severe issues involving standing water or excessive humidity levels that could lead to mold problems in wet drywall and insulation materials, professional help might be required for prompt mold remediation efforts.

Steps to Stop a Toilet From Overflowing

overflowing toilet in bathroom

To stop a toilet from overflowing, first, turn off the water supply; second, clear the clog using a plunger or auger; third, adjust or replace faulty fill valve or flapper valve; fourth, reduce water pressure.

Turn off the Water Supply Valve

One of the first and most important steps in stopping a toilet from overflowing is to turn off the water supply valve. This can prevent further damage to the toilet and bathroom floor, as well as reduce the risk of water damage spreading throughout your home.

The shut-off valve for the toilet’s water supply can usually be found behind or beside the toilet, near the wall. It may be a knob that you turn clockwise to shut off the flow of water, or it may have a lever that you flip downwards.

Once you have turned off the water supply, it’s important not to flush or use any other plumbing fixtures until you have addressed the issue causing the overflow.

Clear the Clog Using a Plunger or Auger

When dealing with a clogged toilet that is on the verge of overflowing, using a plunger or auger can be an effective solution to clear the blockage. Firstly, ensure that the water covers the cup of the plunger and manually control the flapper if necessary to allow enough water into the bowl.

With a tight seal against the hole, create rapid suction by repeating five or six push-pull motions.

If these efforts don’t work, try using an auger instead – also known as a toilet snake or drain snake. Insert it into the drain hole until it reaches the clog and turn clockwise to break up any obstruction.

It’s essential to remember that turning off your toilet’s water supply before attempting either method is crucial in order not to cause more damage during cleaning. If you are unable to clear away stubborn clogs yourself or face significant water damage from flooding, seek professional help promptly.

Replace Faulty Fill Valve or Flapper Valve

If you’ve tried plunging your clogged toilet and it’s still overflowing, the issue might be caused by a faulty fill valve or flapper valve. The fill valve is responsible for refilling the tank with water after a flush, while the flapper valve controls the flow of water from the toilet tank to the bowl.

Sometimes these valves can malfunction, causing continuous running or overflows.

The good news is that fixing them doesn’t always require professional help. Homeowners can use basic tools like pliers and hacksaws to replace these parts in just a few simple steps.

Reduce Water Pressure

Reducing water pressure is an important step to prevent your toilet from overflowing. High water pressure can cause the fill valve to malfunction, leading to a continuous flow of water into the bowl.

This excess water can eventually spill over and result in an overflow.

It’s also important to note that reducing water consumption by limiting toilet flushes or fixing leaks can help lower the overall pressure in your plumbing system. By taking these steps, you’ll not only prevent potential overflows but also save on your utility bills and conserve precious resources.


A toilet overflowing can be quite messy and potentially hazardous to your home – structural damage, leaks, and mold growth can all result from a little clog. However, following some of the prevention measures we outlined above can help stop minor clogs or overflowing toilets pretty easily – without the need for professional assistance. 

Sometimes DIY isn’t possible, and you’ll need to contact a professional plumber, like us at Allphase Restoration. This may include work like adjusting or replacing faulty valves.

Understanding the common causes of toilet overflows can help you take preventative action, but if you experience an emergency situation, we can respond immediately. Don’t hesitate to contact our IICRC certified technicians today! 

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