How to Repair a Leaking Toilet Seal

This month we’re back in the bathroom with a leaky toilet. This time it’s an external leak (meaning that there's water on the bathroom floor) which, as we saw in the previous leak detection post, gives 2 basic possibilities:

1.       Leaks from the cistern – the toilet leaks and refills continuously causing an ever increasing amount of water on the bathroom floor.

2.       Leaks from the bowl or outlet – the toilet leaks during or after the flush leaving a small puddle on the floor. The quantity of water is limited since the cistern doesn’t refill.

The possible sources of these types of leak are:

1.       Leaks from the cistern

a.       Cracked or damaged cistern

b.      Leaky seal between the cistern and the pan

2.       Leaks from the bowl or outlet

a.       Cracked bowl

b.      Leaky toilet seal or flange

Cracked cisterns or toilet bowls can be repaired with an epoxy filler or repair-all type putty.

Damaged seals or flanges need to be replaced

Sometimes a good seal leaks because the cistern or bowl isn’t firmly fixed in place leak because of movement.  Check the bolts which hold the cistern to the bowl and the bowl to the floor are correctly tightened.  A toilet or cistern which rocks will often leak.

Visual inspection will show which of the causes mentioned above are to blame.

In this case we find drips coming from the toilet pan outlet seal. Closer inspection reveals that the rubber is perished and cracked. The solution is to replace the seal with a new one.

How to Replace a Leaky Toilet Seal

Toilet Repair Step 1

Fill a bucket, the sink and the kettle with water. We’re going to turn off the water at the main stopcock so we’ll need water to clean up, wash our hands (believe me you’re going to want to wash your hands several times during this process!) and of course make a cup of tea!

Toilet Repair Step 2

Turn off the water at the stopcock – there may be a small tap mounted on the wall at the inlet to the cistern, but in my experience these valves frequently leak. It’s always best to turn the water off at the stopcock.

Step 3

Flush the toilet to empty the cistern, undo the two plastic wing-nuts which connect it to the toilet bowl and lift the cistern clear (empty any residual water into the bath or the toilet and put the cistern carefully to one side)

Step 4

Remove the seal between the cistern and the toilet bowl. Depending on its condition you can either re-use it or replace it with a new one (Even thou the existing seal didn’t leak I decided that it would be a good idea to replace it with a new one when reassembling everything – preventive maintenance)

Step 5

Unbolt the pan from the floor. The are two bolts which fix the pan to the floor. We use a 10mm spanner to remove the cap-nuts. It’s possible that the nuts have corroded onto the bolts in which case the bolt will most likely release from the rawlplugs in the floor. If by a stroke of bad luck they don’t release easily from the rawlbolts in the floor then you may need to cut the nuts off using a dremel (or similar tool) and mini cut-off disk.

Step 6

The Toilet pan can now be lifted clear of the 2 fixing bolts and pulled away from the waste pipe.

Step 7

Tip the water from the toilet bowl into the bath.

Step 8

Remove the damaged toilet seal and (in order to ensure that the new seal seals) clean up both the outlet from the pan and the entrance to the waste pipe. Believe me, you will want to wash your hands after doing this!

Step 9

Remove the bolts from the floor; this is best done with mole grips. Take care not to damage the threads when doing this.

Step 10

Fit the new seal to the waste pipe and slide the toilet bowl into place, taking care to make sure the seal seats correctly against both the waste pipe and the exit from the toilet bowl.

Step 11

Replace the nuts and bolts which hold the toilet pan in place. Tighten down each side bit-by –bit to make sure that the toilet is correctly aligned and firmly seated.

Step 12

Empty the bucket of water into the toilet to perform a test flush and ensure that the new seal doesn’t leak. If it leaks, it will be necessary to disconnect the bowl again and re-seat the seal.

Step 13

If the toilet doesn’t leak then we proceed to re-connect the cistern and open the stopcock.

Step 14

Perform a test flush to make sure that everything works correctly and that there are no leaks.

Step 15

Clean up any mess and wash your hands!

Alternative Types of Toilet Seal

The rubber seal shown in the photos is very common. You may also encounter more elaborate seals or the old fashioned wax seal. In the case old the wax seal we simply cut the donut into two pieces, insert the two parts into the gap between the toilet and the waste pipe. We then use the heat from our hands to mold the wax into place until a hermetic seal is formed. The other plastic seal is simply inserted into the drain pipe and the toilet is slotted into place. Another possibility is that the toilet sits on-top of the waste pipe and there is a seal in a flange which is fitted into the floor below the toilet. These types of seal are similar to those which we have seen and the symptoms and replacement process are basically the same as described above.

How To Diagnose a Leaky Toilet

In my previous posts on how to repair a leaky toilet I'd already worked out where the leak was and went straight ahead and replaced the flush mechanism with a water saving dual flush mechanism, although I did mention how you could fix the leak.

I thought I'd better put that right by explaining how to find and fix the most common leaks.

When a toilet starts to leak it generally leaks into the pan and down the drain.

There are 2 types of leak:

1. The toilet is overfilling , causing the water to run out through the overflow tube.(Which on most toilets runs into the toilet bowl ,on older toilets the tube may go straight outside).
2. The flush mechanism isn't water tight causing a leak, also into the bowl.
   So the first thing to do is decide which type of leak we have.

The easiest way to do this is to simply turn off the water supply.

If the toilet is overfilling and water running thru the overflow pipe then once the water level in the cistern has dropped to below the level of the overflow pipe it will stop overflowing. The toilet then stops leaking and the water in the cistern stays at this level. This is leak type 1 and is sometimes described as a running toilet. This indicates a problem with the fill valve or the float.
If , on the other hand the toilet keeps leaking until the cistern is empty then the problem is with the flush mechanism.

Now we know where the problem is – we just need to find it.

Solving Type 1 LeaksIf the toilet is overflowing it could simply be because the fill level is set too high.

In which case we simply need to lower the water level to below the height of the overflow tube. This can be done in one of 2 ways depending on the mechanism fitted. If we have an older ball and rod style float then the level can be lowered by simply bending the rod down slightly.

If we have a more modern style float , as shown in the photo, then the level is lowered using the adjustment screw.


In either case if adjusting the float height doesn't solve the leak then the inlet valve is probably faulty and needs to be repaired or replaced.

Solving Type 2 LeaksIf the flush mechanism is leaking then there are three possibilities:

• The flush valve is obstructed or not shutting fully. (This is especially probable if its a very old toilet where the valve is a simple flap) In this case once the obstruction is removed and the valve can close properly then the toilet will stop leaking.
• The flush valve closes properly but leaks. In this case check the state of the gasket , if its perished or otherwise damaged (as shown in the photo) then it needs to be replaced. Once the gasket is replaced it will stop leaking.
• If the flush valve seals correctly but the mechanism leaks then check the “O”-rings or gaskets which seal where the mechanism attaches to the cistern. If these are perished or damaged they may cause a leak and need to be replaced.

If the toilet is running or leaking into the bowl then one of the above methods should fix it.

If the leak is outwards (onto the bathroom floor) then it could be due to A cracked cistern , The seal between the cistern and the pan, the seal between the flush mechanism and the cistern, or the seal between the toilet and the drain. If its a faulty seal then it will normally leak when the toilet is flushed . If its a cracked cistern then it will generally be a continuous leak. More information about diagnosing external leaks can be found here.

How to Fix a leaky toilet- Part 6

Toilet Repair Step 9
Next we fit the water inlet valve to the cistern. This simply passes thru the hole in the side of the cistern and is bolted on using the 2 plastic washers and the 19mm nut provided. Don't over-tighten it – just nip it up. Make sure that the float mechanism is roughly vertical. Once in place the flexible water pipe is attached and the stopcock opened.

As the cistern starts to fill with water. Check that there are no leaks anywhere !!!
The fill level is adjusted using the small plastic screw on the float mechanism.(see photo)
There are 2 marks on the flush mechanism marked “min” and “max”. The float mechanism should be adjusted so that the water fills to between the two marks.

Toilet Repair Step 10

Next adjust the level of the threaded rod which triggers the flush mechanism so that it is about 1 cm below the top edge of the cistern. This is just a rough adjustment at this stage so no need to do up the red lock nut.

Toilet Repair Step 11

Fit the Chromed Flush button to the lid of the cistern as shown in the photo and put the lid in place.
The last step is to re-adjust the length of the plastic threaded rod 'till the blue line on the button just disappears. (You can just about make the blue line out in the close-up photo below)

This might take a bit of trial and error.

That's it ! Easy as that. You now have a non-leaky and water saving toilet. It really is one of those jobs that takes less time to do than to explain how to do it !

How to Repair a leaky Toilet - Part 5

Toilet Repair Step 8 Now we are ready to re-connect the cistern to the pan. It may be necessary to clean up round the hole where the the cistern connects to the pan.

Before we fit the cistern we place the thick rubber gasket which seals the cistern to the pan.
The gasket which comes in the kit is a big silicon rubber affair that should do a good job – no mastic needed !!!!







Next the cistern is lifted into place and the wing nuts which hold it in place are done up – again there's no need to go crazy here only hand tight.

Its best to do each side a bit at a time so that the cistern stays level.



As you can see in the second photo. The Cistern is remounted with just the red fitting in place and is now ready for the flush mechanism to be attached.




Toilet Repair Step 9 fit the flush mechanism

Before fitting the flush mechanism to the toilet.

We set the flush to its minimum setting using the red plastic tabs visible in the photo. At a partial flush of 3L and full flush of 6L it still gives a powerful flush.

The flush-mechanism clicks and locks positively into place on the red plastic fitting, which we've previously secured in the cistern.

How to Repair a leaky toilet - Part 4

The next stage is to clean the cistern if necessary and fit the new flush mechanism to the cistern.

I decided to fit a “Fominaya – Eco Cyclon”
I chose this model because It allows you to adjust the amount of water used in both the full and partial flushes.It also has different fittings to fit different makes of toilet - it should fit any model.

(Note: I also decided to fit a more modern float mechanism instead of the old ball type – coz they're easier to adjust and I figure that while everything's in pieces I may as well give the toilet a complete overhall.In this case the shut off valve is made by Wirquin. )

Toilet Repair Step 7

Select the correct adapter for your cistern and fit it to the cistern, There are 2 gaskets supplied to seal it so that no water leaks out. (Its not very easy to see in the photo but theres a rubber gasket (washer) on the inside of the red fitting and a plastic disc on the outside to protect the cistern from the tightening Ring.
At this point its worth mentioning that the fitting only needs to be tightened by hand – theres no need to over-tighten it with tools , just do it up as tight as you can by hand.

How to Fix a leaky toilet - Part 3

Once The Cistern is removed from the pan you will see that the flush mechanism has a threaded section which passes thru the toilet cistern and is fixed by a plastic threaded collar and 2 rubber washers. If these washers were perished then the cistern would probably leak " externally" ie. onto the bathroom floor – which is not the case here (actually this would largely depend on the seal between the cistern or the pan).

Anyway, we unscrew the plastic collar ( it may need a light tap with the hammer if it has a lot of lime-scale as is the case here , no need to go crazy a few light taps should do it) and remove the old , leaky , flush mechanism from the cistern.

Once the flush mechanism is out of the cistern we can see what is causing the toilet to leak. The main seal on the flush mechanism is badly perished (see photo) and because of this doesn't seal , causing a continuous leak into the toilet.

At this point if you just want to fix the leaking toilet you could just clean everything up , replace this seal and put everything back together. However for the reasons mentioned earlier, I've decided, rather than just repair the leak , to update to a double flush system to save water, and in the long term money (and the planet !!)

How To Fix a Leaky toilet - Part 2

So The waters turned off . By the way if theres one of those small taps on the wall by the toilet (as in the photo above)
don't trust it , in my experience they normally leak. Turn the water off at the main stopcock !

Toilet Repair Step 2 Flush the toilet – this empties the cistern (well about 98 % anyway)

Toilet Repair Step 3 Unscrew the old flush mechanism actuator so that you can take the lid off the cistern.

Toilet Repair Step 4 Disconnect the flexible pipe from the float mechanism on the side of the cistern ( 17mm spanner) and then remove the float mechanism from the cistern (19mm spanner )

Toilet Repair Step 5 Use the old towel or rags to absorb the last of the water left in the toilet cistern. (see photo)

Toilet Repair Step 6 Undo the Plastic wing-nuts which connect the cistern to the pan and lift the cistern free.

How To Fix A Leaky Toilet - Part 1

I've got a few water saving repairs to do around my home so I thought I'd start a Blog to show you how and also why you should do them !

How to Repair a Leaky Toilet.

My toilet's been leaking for a few weeks. This not only is annoying , due to the sound of running water, but it also costs money as it consumes water. So I'm gonna fix it but also, I'm going to update the toilet's flush mechanism to a modern double flush system. This makes sense because its not going to take me any longer to do and whereas my toilet used 10l with every flush with the new mechanism fitted its going to use only 3L for a partial flush and 6L for a full flush. It might not seem like much difference but if you do the calculation for a family of four you'll see its going to save a lot of water. If your water is metered that equates to a substantial cash saving on your water bill. If not well at least you can be content that you're helping save the environment every time you go to the toilet !!!

So Here it is

How to Repair a leaky toilet.

This job takes about half and hour from start to finish.

Tools : you will need to repair your leaky toilet:

• 19mm spanner (or an adjustable spanner)
• 17mm spanner (or an adjustable spanner)

• Philips Screwdriver (medium)
• Small nylon faced hammer ( in case the old flush mechanism is locked on by lime-scale)
• Old rags or an old towel (to absorb water)

Toilet Repair Step 1: TURN OFF THE WATER AT THE STOPCOCK !!!

Actually before you do its worth ; (a) filling a bucket with water - in case you need some water.

(b) filling the kettle - in case you want to have a cuppa!