A gravity flush toilet depends on gravity to transfer water from the tank to the bowl, where a siphon is created in the toilet trap in order for flushing to occur.
To have a strong flush, a decent amount of water needs to be dumped from the tank to the bowl within a very short time. It is the process of dumping a large volume of water within a short time that creates a strong siphon, and therefore a strong flush.
A toilet that flushes slowly and incompletely is caused by clogs, low water level in the tank/bowl, clogged siphon jet and rim holes, loose flapper lift chain or a flapper that closes too fast. A toilet’s age will also affect how well it flushes.
To increase the flushing power of a toilet, start by checking if the drain is clogged. Adjust the water level in the tank and bowl, unclog siphon jet and rim holes, adjust the flapper lift chain slack or install an adjustable flapper. If all fails, replace the toilet with a modern strong flushing one.
If your toilet leaves paper after flushing, it is a sign that enough water is not getting into the bowl or there is a partial clog in the toilet trap or drainpipe. Adjusting the tank’s water level, unclogging rim jets and unblocking the toilet drain will solve the problem.
If you have to hold the toilet flush lever down in order to get a good flush, there is a problem with toilet flapper. Either the lift chain is too loose or the flapper is not opening up fully to allow water in the bowl.
A toilet that flushes and then waste comes back is almost always caused by a clog in the trap or drainpipe. That is usually a partially clog that can be fixed by either plunging the toilet or snaking it.
How to Adjust a Toilet Flush Pressure/Power
If you are a having a slow/weak flushing toilet whose power you want to increase, the problem is with one of the problems I have mentioned above and rarely will you find a combination of 2 or more problems.
The route to take in fixing the situation will therefore depend on the root cause of the problem.
The following are the different ways to increase your toilet’s flush power:
1. Check if the Toilet is Clogged
The first thing you should do is to establish if the problem is with water delivery into the bowl, or it is caused by a clogged P-trap or drainpipe.
A toilet P-trap is the curved section which is connected to the drainpipe. It has a short leg which goes up and a long leg which goes down and is connected to the drainpipe. This is where the siphon effect takes place.
Due to the shape of this part of the toilet, it tends to clog a lot. A clog can either be a solid one or a partial one.
A solid clog will not allow waste or water to pass through. If your toilet has a partial clog, it will drain slowly, and you will notice that water will rise in the bowl before draining out. It may also not flush out toilet paper.
To find out if the toilet is clogged or the problem is with the toilet tank, fill a bucket with water and dump it all at once inside the bowl. This is better done after using the toilet (for the number 2) when you have both poop and toilet paper in the bowl.
If the toilet flushes strongly, the problem is with the water delivery from the tank to the bowl. On the other hand, if it is drains slowly and even overflows, you definitely have a clogged toilet.
Note: if apart from a weak flushing toilet you are also experiencing slow draining fixtures (tubs, showers and sinks), you could be dealing with a blocked plumbing vent or even a clogged main drain stack.
To unclog a toilet, grab a toilet plunger and plunge aggressively for a few minutes. Flush the toilet to see if there is a change in flushing power.
If the plunger doesn’t seem to do it, you will need to upgrade to a toilet auger/snake. The snake will hook and pull out solid clogs or shred them into smaller pieces.
2. Adjust the Tank and Bowl Water Level
In order for a toilet to flush powerfully, the water level in the toilet bowl and toilet tank has to be just right. If the water level in the bowl is low, there is a chance that the water level in the tank is low as well.
Let us start with the toilet bowl water level. How do you know what the level of water in the bowl should be?
Take a pencil and mark the current toilet bowl water level. After that fill a bucket with water and dump it inside the bowl.
If the new water level is higher than the previously marked one, the water level in your bowl is lower than it should be and you will need to adjust.
From there proceed to the toilet tank. Lift off the tank lid and place it away in a safe place where it cannot fall off and break.
Check the water level inside the tank. Ideally, the water level inside the tank needs to be ½-inch from the top of the overflow tube.
If yours is lower than that you will need to adjust it. By adjusting the water level in the tank, you will be ensuring that more water flows to the bowl to create a stronger siphon.
How to Adjust the Water Level in a Toilet Tank
To adjust the water level in your toilet tank, you will only need a Philips screwdriver. The first thing will be to determine if your toilet uses the old-style float ball (ballcock) or a float cup.
If you have a float ball, look for a screw where the float arm is connected to the fill valve. By turning the screw clockwise using the screwdriver, you will manage to increase the water level in your toilet tank.
If you have a float cup, it will be attached the vertical length of the fill valve. Look for a long plastic screw connected to the float. You can use a screwdriver or even your bare hand to turn the screw clockwise and increase the water in your tank.
As I had mentioned earlier, increasing the water lever in your tank will also increase that of your toilet bowl. There are however exceptions.
Start by checking if the refill tube is connected to the top of the overflow tube. A refill tube is thin tube connected to the overflow tube from the fill valve.
When the fill valve is filling the tank after flushing, the refill tube sends some water down to the bowl via the overflow tube (flush valve) to ensure that the water level in the bowl is just right.
If the refill tube has detached from the overflow tube just attach it back. Alternatively, you can buy a better fill valve with an adjustable refill tube like the Fluidmaster Performax Fill Valve (on Amazon) which also refills your tank faster.
3. Unclog the Siphon Jet and Rim Holes
Water from the tank enters the bowl via tiny holes around the rim of the bowl called rim holes, as well as a hole at the bottom of the bowl in some models called a siphon jet.
The siphon jet is straight opposite the bowl outlet. This way, it is able to push water straight into the trap for a stronger siphon and therefore a better flush.
With time, rim holes and siphon jets get clogged with minerals (especially calcium) more so for folks who live in areas with hard water. Clogged rim holes and siphon jets restrict the flow of water from the tank to the bowl and therefore a weak, slow and incomplete flush.
Here is how to unclog a toilet siphon jet and rim holes and increase flush power:
- Turn off water to the toilet. The shut off valve is on the wall behind the toilet.
- Flush the toilet and hold the toilet trip lever down to remove as much water as possible.
- Use a toilet plunger to force as much water as possible out of the bowl and down the drainpipe. Soak the remaining water from the bottom of the bowl using a cloth until the bowl is completely dry.
- Dump 2 or 3 cups of vinegar in the bowl. You need to make sure that the siphon jet is covered with the vinegar.
- Lift off the tank lid and place it away.
- Pour another cup of vinegar down the overflow tube. This vinegar will dissolve the calcium blocking the rim holes.
- Wait for an hour or longer if you can.
- Insert a thin hose inside the siphon jet and snake it to remove as much calcium as you can. You can even use a finger.
- Poke through each rim hole using an L-shaped Allen wrench of the same size to make sure that they are all open.
- Turn water back on and flush the toilet severally. You will notice an improvement in flush power.
To prevent the rim holes and siphon jet from clogging, pour a cup of vinegar down the overflow tube from time to time. Squirting a generous amount of dish soap also helps.
Note: Some people use muriatic acid instead of vinegar for the above job. While muriatic acid is stronger than vinegar, it is bad for your plumbing, unsafe for the environment, bad for the toilet’s finish and should never be used by folks on a septic system.
4. Adjust the Lift Chain’s Slack
A toilet handle is connected to the toilet flapper using a lift chain. Pushing the toilet handle down puts tension on the chain which in turn lifts the flapper off the flush valve allowing water to enter the bowl.
If the lift chain is too slack, the flapper will not open fully meaning that less water will enter the bowl and therefore a weak/slow flush. Ideally, a lift chain should have a ¼-inch slack.
Lift off the tank lid and try to push the handle down. Check if the flapper is opening up fully or just half. Adjusting the lift chain slack is easy though it is through trial and error meaning you will need to do it several times before you get it right.
Another thing you will want to ensure is that the lift chain is connected perpendicular to the top of the flush valve/flapper. If the lift chain is lifting off the flapper at an angle, the flapper will not open up fully and less water will be available to give you a strong flush.
5. Install an adjustable Toilet Flapper
Another thing you can do to send more water down to the bowl is install an adjustable toilet flapper. Both Korky and Fluidmaster have decent options to choose from.
An adjustable toilet flapper allows it to stay open for long time during flushing. By so doing, more water will exit the tank and enter the bowl.
6. Replace your Toilet with a New One
As I mentioned earlier, the trick to having a strong flush is through delivering water to the bowl very fast. If you have an old toilet, chances are that it uses a lot of water but does not have a strong flush as the modern ones which uses less water.
What modern toilets have different from old toilets is a big flush valve. They have a 3-inch flush valve (some even 4-inch) unlike the 2-inch flush valve in your old toilet.
The big flush valve allows the sudden dumping of water inside the bowl and hence the strong flush. Replacing a toilet is not a cheap undertaking but if you are desperate for a water-efficient and strong flushing toilet then that may be you only alternative.
And basically that is how to make a toilet flush better/strongly. I hope this guide was of help to you.