Toilet Has A Weak Flush: What Should I Do?

Pushing down on a toilet’s handle has an expected outcome. You should be able to hear the sound of water filling up the bowl before the gurgle as it gets pushed into the drainage system of your home or business. 

Yet, there can be times when a weak flushing toilet prevents all of the bowl’s contents from going down. 

No one wants to waste water and money by having to flush a second time. Fortunately, there are many solutions you can try to fix your weak toilet flush. If none of these solutions work or if you suspect the reason is far more severe, you can always contact our team at Diamondback to schedule an appointment.

4 possible reasons why your toilet has a weak flush

When it comes to your toilet and its plumbing, a weak flushing toilet can be caused by one of many different factors. The first thing you need to consider is a partially clogged pipe in the toilet’s plumbing due to the fact some of the water still drains away. If that isn’t the cause, try out some of these other potential solutions before you call.

Reason #1 — The water level in the toilet bowl is too low

To start troubleshooting the cause of your problem, compare the water level in your toilet bowl with the level in the tank. If you find that the water inside the tank looks normal but the water in the bowl is lower, the cause is a cracked fill valve. To make sure that the part is the cause, flush the toilet with the lid off and check for any water squirting out from the top of it.

Depending on your toilet’s model, the fill valve will be on a lever on the opposite end of a balloon-like part called the float. This is the part of your toilet that opens to fill the tank. Any excess water that’s in the tank flows down through the overflow tube and to the bowl. 

When the fill valve is cracked, the water that leaks out of it can cause the tank to fill up properly but without much water filling the bowl. The valve essentially shuts earlier than it’s supposed to.

So, the best way to fix a weak flush here is to replace the faulty fill valve. To do this though, you’ll need to disconnect the water supply, close the toilet shut-off valve from behind the toilet and drain out the water into a bucket. From there, though, replacing the fill valve is finding and removing the valve nut.

Reason #2 — The water level in the toilet tank is too low

On the other hand, if the water level in the tank is too low, the most likely reason that your toilet has a weak flush is the float cup or ball. The float is the part that shuts off the fill valve, so if the part is too low, the tank’s water level will be too. All tanks have a specific water level that it fills to and any water below that level will cause the flush to be weaker.

To fix this, you’ll need to move the float up. Fortunately, many toilets have a small adjustment screw close to the float that shifts the height when loosened. All that’s needed is to use a screwdriver to move the float up further. If the water inside the tank is too high, the water will continuously flow into the overflow tube, so make sure that you look out for any markings that show the ideal water level!

Reason #3 — The flapper valve’s chain has too much slack

If the water level in both the tank and bowl is fine, check how long the chain is that connects the tank’s stopper – or flapper valve – to the rod above it. Whenever you flush, the chain lifts the valve, releasing the water inside the tank out into the bowl. But if the chain is too large, little to no water drains out from the tank, resulting in a weak flush.

Adjusting the length of the chain to remove that extra slack is another quick weak toilet flush fix since most handle rods have clips that connect to the flapper valve’s chain or the chain itself is clipped onto the rod above it. If your toilet doesn’t have a clip on either, you’ll need to use wire cutters to reduce the chain manually. In both cases, make sure to leave enough length to let the valve shut naturally.

Reason #4 — Your toilet’s siphon jet is clogged

Sometimes called a jet flush hole, the siphon jet is the part of your toilet that pushes the waste and wastewater out of the bowl every time you flush. Since it’s at a slight angle, calcium and other mineral deposits can form in the opening. Over time, the deposits build up until the siphon jet is partially clogged, leading to weak toilet flushes. 

When it comes to learning how to fix a weak flushing toilet it’s as simple as cleaning out the siphon jets. You’ll want to turn the water off before pouring a bit of an acidic toilet cleaner into the bowl. Then, using a brush with a small enough head, clean out the siphon jet by giving the brush a few twists. Flush the toilet to check if it’s now clean. If it isn’t, simply repeat the process and pour some into the bowl to test it again.


There are many possible signs and reasons that you’re dealing with a weak flushing toilet, though these are some of the simplest to fix without the need to call a professional for help. If the issue isn’t with any of the tank’s parts, check to see that the bowl itself is clean and unclogged. 

You can also use a plunger to try and loosen any partial clogs there might be in the plumbing, but if neither it nor the fixes we provided above solve the issue, you can always rely on our team at Diamondback.

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