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The Home Depot

Why Is My Overflow Pipe Leaking?

Pro Referral > Home Guides > Plumbing > Why Is My Overflow Pipe Leaking?
Why Is My Overflow Pipe Leaking?

A leaking overflow pipe is more than just an irritant. It leads to water waste and frequently damages the structure or other surfaces of your home as well. Besides, damp walls can lead to the formation of mold that requires costly remediation and can even cause health problems in the form of allergies. All of these various problems can be eliminated by fixing the leak in the overflow pipe. As the overflow can be caused by a variety of reasons, you need to examine all of the factors detailed below to identify the cause and resolve the issue.

  1. 1.Water Pressure is too High

    One reason for an overflow pipe to leak is due to very high water pressure in the tank. This will force the water out of the overflow pipe constantly. To fix this problem, check the inlet valve that controls the flow of water into the tank and close it partially. This should lead to a lower water pressure and ensure that the overflow pipe does not leak any longer. Often, the inlet valve for the overhead tank is placed in the kitchen or near the tank.

  3. 2.Worn Washer

    Another reason for a leaking overflow pipe is a worn washer. The washer of the float valve can wear out because of the constant immersion in water and the sediments in it. This can be fixed by replacing the worn washer with a new one. Before your remove the float valve and dismantle it to check the washer, you need to completely close the inlet valve to the tank to ensure that it does not overflow and flood the area. Once you have dismantled the float and located the washer, you can take it to the hardware store and ask for a similar one. By attaching this to the float, you can ensure that the overflow pipe stops leaking.


    An overflowing pipe increases your expenses in two ways – a higher water bill and an additional bill for repairing the damage caused by the over flowing water. The best way to ensure that your expenses from these causes are minimal is to fix your leaking overflow pipe as soon as possible. Why would you want to spend money every month on water you do not use? It is also a waste of resources from the community. In addition, this extra water that you are paying for could eventually cause serious damage to the surrounding walls or cabinets.

  5. 3.Bad Float Valve

    If the washer of the float valve is fine, the cause of the leaking overflow pipe could be a damaged float valve. The float valve itself could be broken and no longer floating. If the ball of the float valve has developed a hole and water has entered it, it can no longer effectively function. If you find water inside the ball of the float valve you should replace the entire unit. Again, before you remove the float valve, you need to ensure that the inlet valve is completely closed. It is best to take the damaged float valve along to the hardware store when going to purchase a replacement so that you can get the same model. This will make it easier to fix the float valve in your tank.

  7. 4.Toilet Cistern

    When the overflow pipe of the toilet cistern leaks water, you need to follow the same steps outlined above as the mechanism of the float valve is the same. In the case of a toilet cistern, you can easily remove the top and examine the float valve and ensure that it is floating properly. Sometimes, the stem of the float valve becomes tangled in the chain or becomes bent and moves closer to the valve of the cistern. This can cause it to malfunction. In that case, all you need to do is gently disentangle the float valve from the chain mechanism or straighten the stem of the float valve to fix the problem.

  9. 5.Cold Water Tank

    To check if the water is overflowing from the cold water tank, you need to open the cold water tap in the bathroom and leave it open for some time. This will reduce the water level in the cold water tank and stop the leak. If the leak continues even after the water level in the cold water tank falls, you should look for the problem elsewhere.

  11. 6.F & E Tank

    The Feed and Expansion tank or F&E tank can also leak water from the overflow pipe. Since it is difficult to identify the problem as coming from this tank, you need to eliminate the other possibilities first. If you are sure that the leak from the overflow pipe is not from a toilet cistern or cold water tank, then you should examine the F&E tank. As oxygen enters the F&E tank, it can easily corrode the float valve mechanism within it. As such, you need to replace the float valve mechanism in the F&E tank to stop the leak from the overflow pipe.

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