Cistern leaks are a common household problem, and will also affect the cleanliness and hygiene of the toilet. If you find that your has leaks, you can try the following methods to solve this problem:

Leaky Cistern; This is a cover photo for the article, showing the appearance of a toilet tank, the toilet tank is a device that controls the amount of flush water, if the tank leaks, it will affect the cleanliness and hygiene of the toilet. This article will teach you how to replace the tank yourself to solve the toilet tank leak problem.

Leaky Cistern and How to Fix it

Check if the float in the cistern is working properly

The float is part of an inlet valve that controls the water intake of the tank. When the tank is full, the float closes the water inlet to prevent more water from entering the tank.

If the float is damaged or improperly adjusted, the water level in the tank may rise above the overflow pipe, causing the toilet to run continuously. If the water level is too low, it will affect the flushing power.

To check if the float in the tank is working properly, you can follow these steps:

Open the cistern’s cover and observe the height of the float. Gently pull on the float with your hand to see if it stops the water from flowing in. If it doesn’t, you may need to replace the float.

Try adjusting the water level in the tank to an appropriate level using the inlet valve.

Leaky Cistern; from book : I S B N:978-7-5083-4945-9; This is an illustration showing how to adjust the inlet valve inside the toilet tank. The inlet valve controls the water flowing into the tank. When the tank is full, the inlet valve closes to stop more water from entering. If the inlet valve is damaged or improperly adjusted, the water in the tank could rise above the overflow pipe and cause leaking. You can try gently pulling the inlet valve by hand to see if it stops the water. If it doesn't, you may need to replace the inlet valve.

Leaky Cistern; from book : I S B N:978-7-5083-4945-9; This is an illustration showing how to adjust the inlet valve inside the toilet tank using a screwdriver. The inlet valve controls the water flowing into the tank. When the tank is full, the inlet valve closes to stop more water from entering. If the inlet valve is damaged or improperly adjusted, the water in the tank could rise above the overflow pipe and cause leaking. You can use a screwdriver to counter-clockwise unscrew the inlet valve, take out the rubber flapper in the middle, check it for damage. If damaged, you can purchase a replacement rubber flapper. If undamaged, you can use warm water and a toothbrush to clean out any sediment or hard water buildup.

The images show how to adjust the water level in your tank. Tanks may have different inlet and outlet valve assemblies, but they work on similar principles.

Check if the flush valve and gasket in the cistern are working properly

The flush valve is a device that controls the water volume released when you push the flush button. It opens to let water flow out to flush the toilet, then closes again.

Leaky Cistern; from book : I S B N:978-7-5083-4945-9; This is an illustration showing how to check if the toilet tank is leaking. Leaks could be caused by issues with the flush valve, gasket, or cracks in the tank housing. You can dry the inside and outside of the tank with a cloth, then place some kitchen towels around the bottom of the tank and where it connects to the toilet bowl. If the towels become wet, it indicates a leak.

If the flush valve does not open/close smoothly or the rubber flapper inside is deformed, it may not close automatically and cause leaks.

You can turn the flush valve counterclockwise to remove the rubber flapper in the middle and inspect it. If damaged, purchase a replacement rubber flapper. If undamaged, use warm water and a toothbrush to clean out any sediment or hard water buildup.

The above explains the water inlet and flushing components of old-style toilets. For more details refer to this article: Cistern of Toilet 101: What You Need to Know About the 2 Different Structures

Leaky Cistern; from book : I S B N:978-7-5083-4945-9; This is another illustration showing how to check if the toilet tank is leaking. Leaks could be caused by issues with the flush valve, gasket, or cracks in the tank housing. You can dry the inside and outside of the tank with a cloth, then place some kitchen towels around the bottom of the tank and where it connects to the toilet bowl. If the towels become wet, it indicates a leak.

Inspect the gasket near the leak location at the bottom of the tank.

Check if the outer cistern shell is cracked or broken

If the outer shell of the tank is cracked, water will seep out from the cracks and cause the tank to leak. This situation is more serious and you should have a professional replace the tank as soon as possible.

Temporary solution for hairline cracks in the tank: If the cracks are small, you can consider using some simple methods to temporarily seal them first, then consider purchasing a new tank or contacting a professional for repair.

Leaky Cistern; This is another photo showing a product for temporarily repairing hairline cracks in the tank. It is a glass glue from Taobao that can be used to seal small cracks in the outer shell of the tank to prevent water seepage. This is a simple and cheap temporary method, but not a long-term solution. You should purchase a new tank or contact a professional for repair as soon as possible.

Silicone Sealant, front view of LE837 glass glue, showing its high quality neutral silicone sealant and professional packaging design. — This is another photo showing a product for temporarily repairing hairline cracks in the tank to prevent water seepage. This is a simple and inexpensive temporary method.

You can refer to the following 5 key steps to replace the cistern yourself:

1.Turn off the water supply

Find an angle valve near the cistern and turn it to the closed position to stop water from entering the cistern. If there is no angle valve, you need to turn off the main water valve for the whole room or floor.

Leaky Cistern; from book : I S B N:978-7-5083-4945-9; showing how to shut down water input of a toilet

2.Empty the cistern

Press the flush button to flush out all the water in the cistern, or use a manual method to scoop out the water from the cistern.

Leaky Cistern; showing a have flushing a toliet to empty a cistern before uninstalling

3.Remove the cistern

Use a wrench or pliers to loosen the nut at the bottom of the cistern.

Leaky Cistern; from book : I S B N:978-7-5083-4945-9; showing how to uninstall a cistern for repair

Then loosen the nut that connects the riser tube to the angle valve at the bottom of the cistern, and finally separate the cistern from the toilet.

4.Clean the cistern

Use a dry cloth or paper towel to wipe off the water inside and outside the old cistern. To avoid wetting the surrounding environment.

5.Install the new cistern

Follow the instructions of the cistern and connect the new cistern to the toilet, and secure it with nuts.

Then turn the angle valve to open the water supply, and check if the cistern is leaking, and if the flush is normal.