A leaking toilet cistern can waste a lot of water and increase your water bill. However, there are a few things you can do to try and fix it yourself. In this article, we will guide you on how to fix a leaking toilet cistern in a few simple steps.

What is a Toilet Cistern

Basically, a toilet cistern is a small tank that allows you to store water close to the toilet. When we flush the toilet, the water in the tank is released, cleaning the toilet bowl as it moves the waste down into the sewer.

After being used, the toilet cistern will automatically refill so that the next person can use it. It is an essential part of the toilet as without it, the waste would not be able to reach the sewer.

Overview of the Different Parts of a Toilet Cistern

How to Fix a Leaking Toilet Cistern

Finding the source of the leak is essential before fixing a leaking toilet cistern. Following the diagnosis, you can either replace the toilet’s flush valve, repair a leaky fill valve, or just tighten the gaskets to stop the leak.

Diagnosing the Cause of the Leak

A toilet cistern can leak in different places and there are some warning signals that might let you know where it’s leaking. There’s also a test that’s accurate enough for determining whether a leak is present. Here, we’ll walk you through this process.

1. Take the Lid Off the Tank

First, take the lid off the toilet tank. It is on top and it should be simple to remove. Then, carefully place it in a nearby location.

2. Check the Tank’s Water Level

Check the water level in the toilet tank after removing the tank cover. The ideal water level inside the tank is indicated by a certain line that you can see. On the side or back inner wall of the tank, the water level line is typically marked “water line.”

If the water level is above or below this mark, you’ll need to adjust the fill valve. This will ensure that the water level in the toilet tank is appropriate.

3. Perform the Food Coloring Test

You’ll need a few food coloring bottles on hand to carry out this test. It makes no difference what color dye you use. Simply add 15 to 20 drops to your toilet tank’s water, just enough to noticeably change the color of the water, and wait 30 minutes.

4. Check the Color of the Water in the Bowl

Check the color of the water in your toilet bowl after 30 minutes. There is a leak at the flapper or a crack in the overflow tube if any of the dye has made it into your toilet bowl. Then, a repair is necessary.

Replacing the Flush Valve

The flush valve is typically the first thing to look at if water from the toilet tank is leaking into the bowl. The following are the steps for removing the tank from the bowl in order to replace a flush valve and stop the leak.

1. Remove the tank lid, then crank the shut-off valve clockwise to turn off the water.
2. Flush and drain water from the tank as much as possible. Remove any remaining water in the tank using a sponge or towel.
3. Disconnect the following:
   • Tank water supply hose or tube.
   • Flapper chain from tank lever arm.
   • Refill tube that is attached to the top of the overflow pipe.
4. On the bottom of the tank, unscrew the bolts which hold the tank to bowl. Use a slotted screwdriver to keep the tank bolt from turning as you loosen the nuts underneath the tank with an adjustable wrench. Then remove the tank bolts.
5. Lift the tank out of the bowl and place it on top of a cloth or towel.
6. Use a plumber’s wrench to remove the locknut which holds the flush valve to the tank. After that, remove the old flush valve.
7. By carefully following the manufacturer’s instructions, install the new flush valve.
8. After installing the flush valve, reattach the following:
   • Tank to bowl with tank bolts.
   • Flapper chain to flush lever arm.
   • Fill tube to the new overflow pipe.
   • Water supply to the tank.
9. The last step is to turn the water back on, test the new flush valve, and check if there are any leaks.

Replacing a Leaking Fill Valve

A leaking fill valve can result in an excessive amount of water that can trickle into the tank. Eventually, the extra water overflows, and a leaking issue emerges. Check out the following steps on how to replace a fill valve.

1. Turn off the water supply by turning the valve clockwise.
2. Push the flush lever down and hold it for as long as the tank empties. Use a sponge to remove the remaining water from the tank.
3. At the bottom of the tank, where the water supply line enters, loosen the nut. The supply line and fill valve are coupled together by this nut. Then, by using an adjustable wrench, unfasten the nut which holds the fill valve in place.
4. Remove the old fill valve by pulling it up and out of the tank.
5. Install the replacement fill valve by placing it into the opening at the bottom of the toilet tank. Use an adjustable wrench to tighten the nut holding the fill valve and water line in place. Be aware that overtightening can crack the porcelain toilet.
6. Place the overflow line in the overflow tube.
7. Reconnect the water supply line and turn the water supply on. Wait for the toilet tank to be filled with water.
8. Adjust the tank’s water level. Take note that the maximum water level should be about one inch below the top of the overflow tube.

Tighten the Leaking Gaskets

A loose toilet tank-to-bowl gasket, also known as a spud washer, can also be a cause for a leaking toilet cistern. The following steps teach you how to tighten leaking gaskets in a toilet cistern.

1. Turn off the water and flush the toilet to empty the water out of the tank.
2. Find the bolts that connect the tank to the bowl. The flapper at the bottom of the tank is surrounded by two or three bolt heads. The rubber washers under the nuts will help you identify them.
3. Now, tighten these bolts by using a screwdriver and an adjustable wrench. A flathead screwdriver can be used to secure the bolts as you tighten the bolts underneath the tank. The fasteners should also be tightened to stop leakage.
4. Turn the water supply back on and wait as it refills the tank. Then, check for any leaks coming from the bolts. If there is still a leak, you may need to replace the washers underneath the bolts in the tank.

Top Plumbing Services in Brisbane

Here are some plumbing companies in Brisbane that you can avail of if you decide to hire a professional service to fix your leaking toilet cistern. See their contact information.

1. Competitive Plumbing Services

With their clean record of working with local government plumbing sectors, Competitive Plumbing Services ensures high professionalism in their output. They cater their services in all Brisbane Inner City suburbs and the outlying areas.

2. Jabiru Plumbing Services Pty Ltd

Jabiru Plumbing Services is a family-run business serving the greater Brisbane area. They offer a full range of plumbing services, including drainage solutions and gas fitting to both residential and commercial properties.

3. Tri Plumbing Services

TRI Plumbing has already been servicing the state of Queensland for over 40 years. With their extensive experience working with domestic and industrial sectors, they developed a fantastic reputation for providing high-quality plumbing solutions.

4. Soul Plumbing Services

Soul Plumbing pride itself on its fully-certified and highly-trained plumbing team which is committed to delivering superior quality work. With their high value for their clients, they always provide the greatest customer service at fair costs.

5. Botanical Plumbing Services

Botanical Plumbing Services is a locally-owned business that places a strong emphasis on client satisfaction and service. From repairing a leaking pipe to extensive plumbing projects, they offer their services in inner city Brisbane across the South East.

Cost of Fixing a Leaking Toilet Cistern in Brisbane

In Brisbane, hiring a plumber to do toilet repair such as fixing a leaking toilet cistern may cost around $88 per hour. However, the cost can still differ from job to job. 

On the other hand, plumbers take into account a number of factors when quoting for a job. The following can affect the cost of a toilet repair job.

• What type of repair is required
• Time it takes to complete the job
• The materials required for repairs
• Other add-on services

Various Issues That Can Cause a Leaking Toilet Cistern

A toilet cistern and its various components could wear out over time and eventually develop some issues that could lead to a leakage problem. It’s critical to recognize these issues in order to fix them. The following are some of these common issues.

1. Stuck Flapper

Sometimes, a flapper is stuck open which can lead to a leaking toilet cistern. One of the common causes for this is something that might be blocking the flapper, or the chain caught on something in the tank.

It’s also possible that the flapper is not in line with the opening which would cause an overflow. With this, it is recommended to carefully align the flapper to its position. If the flapper appears to be covered in silt, carefully clean it first before replacing it back.

2. Water Valve Was Not Properly Set

Ensure that the water level in the tank is at the water line. If there isn’t enough water, the float in the tank may need to be adjusted, which could explain why your toilet cistern is leaking into the floor. Ensure that the water valve is always turned on.

3. Float Valve is Not Closing

After you adjust the float valve, it is also necessary to check if it is properly shutting off. Try to lift the float and if the water stops running, you will need to adjust the level of the float. Also, check if there’s a need to replace the washer of the inlet valve.

4. Problem with the Drainage System

On the other hand, the leak can be a result of an external issue such as the drainage system. When the drain becomes clogged, the water from the toilet overflows, and the cistern begins to leak. It is recommended to hire an expert to fix this issue.

5. Damaged Flush Pipe Seal

If the leak appears to be coming from a higher level, there might be an issue with a damaged flush pipe seal. In order to replace the seal, the tank must be removed.

A leaking toilet cistern brings a lot of issues such as an increased water bill and damage to your bathroom floor. Thus, it is important to fix it as soon as possible. By simply following the guide in this article, you will be able to fix a leaking toilet cistern in no time.