Why Does My Toilet Have A Weak Flush

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Why Does My Toilet Have A Weak Flush

plumbing issue toilet
Is one flush not enough? Having to flush multiple times before a toilet is cleared can be a hassle. Moreover, it is unhygienic especially when waste is left in the toilet unflushed due to a weak flushing system. Unwanted leftovers can stink up your home and is undesirable.
If you’ve been experiencing problems with flushing in your home toilet, read on to find out why it is happening and how to solve it.

How Does A Toilet Flush Work

Before we find out what is causing a weak flush and how to solve it, we need to understand how a toilet flush works.
Every toilet bowl had a cistern, more commonly known as a tank. Inside the cistern, water is stored to use for flushing. The tank consists of several important parts.
Water enters the tank through the inlet valve. When the tank it empty, it lets water in and stops water when the tank is full. Inside the tank, there is a float ball that rises as the tank is filled with water. The float ball is attached to a float rod that presses against the inlet valve, causing it to stop water entering. This mechanism prevents overflow.
When the flush handle is pressed, the piston is lifter, forcing water to flow through the siphon. This creates suction in the siphon. Then, the water is forced into the toilet bowl through a short pipe. The water swirls around the rim of the toilet bowl, flows down the sides, and leaves through the drainpipe. This process allows the water to clean the toilet bowl and clear the waste as it leaves through the drainpipe.
A drop in water level causes the float ball to be lower. When the float ball is lowered, the inlet valve opens and allows water to flow into the tank so it can be refilled.

How Much Water Should A Flush Use?

The amount of water a flush uses varies with each toilet bowl. Depending on the size and design of the bowl, a different amount of water is needed to completely clear the waste in the toilet.
Some recent and newer models of toilet are more water efficient and require only 6 litres per flush compared to older models that might need 19 litres of water.

Common Causes Of Weak Flush Toilet

1. Water Level

One of the common causes of a weak flush is due to low water level in the cistern of the toilet. More water in the cistern provides a more intense flushing force. Flushing force is required to empty waste in the toilet bowl completely.
With a water level that is below the recommended level, the flushing force is weaker and thus causes the toilet bowl to have a weak flush.

2. Drain Build Up

The next thing to check for is drain build up. If your toilet has a clogged pipeline, it can affect the strength of your flush.
To test for drain build up, pour a gallon of water into your toilet bowl. If the water level in the bowl rises rapidly, it is likely that you have a clogged pipelines.

3. Mineral Build Up

Water enters the toilet bowl from the cistern through jet holes along the rim of your toilet bowl. Over time, minerals can accumulate at the jet holes with every flush. This obstruction weaken the pressure causing the flush to be weak and less powerful.

How To Fix A Weak Flush

While fixing the toilet might seem impossible, there are methods you can try.


If you suspect that your toilet has a weak flush caused by drain build up, try using a plunger to suck out any blockages. Once the blockage has been effectively removed, the strength of your toilet’s flush should be restored.

Remove Minerals

When your toilet bowl has a weak flush due to mineral build up at the jet holes, try using a mineral remover and a screwdriver to clear mineral build up in the jet hole.


To confirm whether or not your toilet is clogged, fill a bucket with cold water and pour it into the toilet bowl. Now, try flushing.
If your toilet still has difficulty flushing or does not completely remove waste, you might have a partial clog. This is where the toilet is not fully obstructed but partially.
To solve this, plunge your toilet thoroughly or use a plumber’s snake.

Adjust Cistern Water Level

Your toilet’s weak flush might be attributed to low water levels. As mentioned earlier, when the toilet is flushed, the tank should be refilled.
To test your toilet cistern’s refilling system, open up the cistern and locate the float ball and the fill line. Try flushing the toilet with the cistern’s lid open and watch the water enter from the inlet valve.
If water stops flowing in before the ball float reaches the fill line then your toilet will not be able to flush strongly. One method that might solve this problem is by adjusting the ball float.

Adjust The Piston

If a piston is out of place or worn out, it can lead to water leaking into the toilet bowl and weak flush. A strong flush is created due to the pressure difference when water suddenly enters the toilet bowl.
To ensure your piston is working well, reposition the chain to give it more strain or slack. If you piston is old, replace it entirely.

Clean Toilet Bowl Rim

Aside from minerals, anything obstructing the jet holes of your toilet bowl could affect the flush strength. As such, it is important to clean the rim of your toilet bowl to remove any obstructions blocking your jet holes.

One Flush Still Not Enough?

After trying the aforementioned tips, your toilet bowl should be back to normal. However, if it is not, you might need to find a professional plumber to look into it for you. Plumbers are able to carry out more high level inspection and troubleshooting that you might not be able to do.

Plumbing Electrical Plumbing Service

Plumbing Electrical Singapore is a 24 hour plumbing service. If you ever need to an emergency plumber Singapore service, we are available round the clock to attend to your plumbing needs. We specialise in both plumbing and electrical works.If your toilet’s weak flushing persists, contact us to help you identify and solve the problem.

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