How to replace the fill valve of a flush system


Just today, the fill valve of my toilet flushing system got damaged.

What happened was water couldn’t fill up the flush tank, and this in turn caused flushing the toilet to be impossible.

I opened the flush tank and figured that the issue was with the water inlet fitting, in which needed to be replaced.

That said, here’s a brief tutorial on how to replace the water inlet fitting of a flush system.


It wasn’t hard to identify the problem. The first symptom was the inability to flush the toilet. This meant that water wasn’t coming out of the tank into the toilet bowl upon flushing. This meant that either the flush valve (outlet for water) was damaged, or the tank was empty.

Upon opening the flush tank, I noticed that the tank was empty.

This now means that it’s unlikely that the flush valve is damaged.  It is however likely that the water inlet system is damaged or misaligned.

Misalignment happens when the float (which is used to control water input) doesn’t function as it should, and get stuck (jammed). This in turn forbids water from entering the tank through the fill valve.

I tried shaking and cleaning the fill valve, but water remains unable to enter the flush tank, hence confirming that the fill valve is damaged.

This therefore meant that the fill valve needed to be replaced in order for the flush system to work.


The first thing to do before repairing the fill valve for a flush system is to identify what type of fill valve is used in the system.

In general, there’s two types of fill valve out there, namely the side inlet fill valve, and the bottom inlet fill valve.

Mine uses the bottom inlet fill valve, which meant that water enters the tank from the bottom of the tank.

Replacing the bottom inlet fill valve is more complicated compared to the side inlet fill valve.

That said, here’s the steps to replace the bottom inlet fill valve of a flush system.


First and foremost, the old fill valve must be removed in order to fix the new one.

Removing it is easy.

Look under the flushing tank for a locknut to the inlet valve.

If you have trouble finding one, there’s a hose connected to the locknut (and fill valve), which is connected to the water source.

Turn off water from the pipe, and then remove the hose connecting the inlet fill valve to the main pipe.

Then, loosen the locknut which is holding the inlet fill valve until you are able to take off the inlet fill valve from inside the tank.


Once the the old inlet valve is removed, prepare the new inlet valve for fitting.

Wrap the screw thread of the new inlet valve with PTFE tape, often referred to casually as thread seal tape.

This tape will improve the tightness at the new inlet valve, hence  preventing leaks through the tank’s inlet valve hole.

It also ensure there’s no leaks when you fix the water hose back at the end of the whole process.

Once that is done, fit the new valve in location, and tighten the locknut slowly until the valve is securely in place. Make sure the screw is tighten just right.

Do not tighten the screw too hard as this may damage the locknut or break the locknut.

Once you are sure the new inlet valve is fixed, reconnect the water hose to the inlet valve thread, and turn on the water.


Once the inlet valve is all in place, the water is turned on to test the new valve.

This initial testing is to see if the new valve works as it should. If it doesn’t, then there probably a need to buy a new inlet valve for the flush tank.

At this point, minor leaks from poor re-connection can happen, but that should be dealt with only after testing the new valve.

If it works well, then the next step is to ensure there’s no leaks with the connections that had been made.


Obviously, poor re-connection will cause water to burst out.

If the pipe system is connected it well, there would be no water leaking out from the connection made.

However sometimes, there’s tiny leaks that go undetected.

To ensure the connections are all leak proof, I would usually wipe dry each and every connection I made with a tissue.

I would then use a fresh tissue and wrap the area I had recently connected.

If there’s a leak, the tissue will get wet and therefore there’s a need to either tighten the joints, or reconnect them properly.

This test is repeated until I am sure there’s no more water leaks from the joints and connections made.

When this happens, the repair of the water inlet is completed.


I bought my inlet valve from a local hardware store for about RM26.

However, I discovered that the valve, or better types of similar valves are sold online for as low as RM10.

The old water inlet valve of mine lasted for over a 10 years, and I would assume the new one would last as long as well.

However, if you think you need to buy such valves, I’ve given the link to buy below.


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