How To Fix A Low-Flow Toilet In 7 Easy Steps

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Last Updated on August 9, 2022 by acechapman

The history of the humble toilet dates back to at least 5000 years. The Indus Valley Civilization and the Romans used primitive latrines. Sir John Harington is the godson of Queen Elizabeth I and was credited with creating the first flushable toilet.

His device required a 2-foot-deep cistern, which was waterproofed with pitch and resin. A filled cistern was located upstairs. Between refilling the cistern, each flush required 7.5 gallons of water. Twenty people could use the flush.

It was several centuries before the Industrial Revolution happened. The flushable toilet was made possible by improvements in the waste disposal and manufacturing processes.

In 1994, federal law required all new toilets to have low-flow. This was in response to an environmental initiative. The flushing water needed for the toilet was approximately 1 1/2 gallons, which is less than half of what was required for older toilets.

How to fix a low-flow toilet? 

how to fix a low-flow toilet

A toilet flush can develop a low flow over time for many reasons. It is quite embarrassing to find out that the toilet flush does not drain completely in one go. You have to wait until the cistern refills again. There are many reasons for this: clogged rim holes; too long handle linkage; as well as the flapper valve may have warped. Low flow could also be caused by external factors such as low pressure in the water supply.

A clogged vent is one common reason. This will then cause a partial vacuum in the cistern, which constricts the discharge. This test should be performed. You can flush the cistern, then open the cover and check for the year of manufacture. We recommend replacing the toilet flushing system if it was manufactured between 1994 and 1997. Low-flow flushing toilets used to require at least two flushes.

You will need the following tools

  • Plunger
  • Toilet auger
  • Gloves for hands
  • Garden hose
  • Sewer auger


  • Too much tension on the chain is the most common reason the flapper valve does not function properly. This will be our first problem. Check the pull on your chain by opening the tank’s top cover. Too much slack can cause the flapper valve to not lift fully. Thus, resulting in a partial flush. Keep the chain in a tight fit. However, leaving just an inch of space.
  • Check the water level at the fill valve cutoff. It should be at least an inch below the overflow pipe mouth. Then, you can shorten the armature to adjust the ball flotation if it is lower.
  • Insert the plunger into the toilet bowl. You should ensure it has enough water. We want to clear a clog with water, not air.
  • If the plunger isn’t working, you can use the toilet auger. It will move as far as it can into the bowl. Clean the head. You can do this several times.
  • If there is no obstruction, examine the opening on the roof. Sometimes, they can become blocked by leaves or debris that blocks airflow to the waste disposal line. Make sure to clear the opening.
  • The garden hose can now be directed through the vent in order to clear out any clogs along the line.
  • If that fails, you can use the sewer auger to clear it.

Common Problems and Solutions for Low-Flow Toilets

Clogged rim jets

how to fix a low-flow toilet

There are a few holes under the toilet bowl rim that allow water to escape from the bowl when the flush is turned on.

These holes can become clogged over time by lime, calcium, and other debris, such as rust. An outflow should be established

You should expect a rapid, pressured outflow. It’s time to get them cleaned if you notice that this is not the case.

You can block the holes with the plumber’s glue. Allow the acidic toilet solvent to be added to the tube. It will dissolve any deposits or buildup in the holes.

After a while, flush the toilet many times. Use a toilet brush to scrub all the debris from the pipes.

Clogged waste pipes

The toilet waste pipe is the one that transports the contents from the toilet bowl into your house’s drainage system and into the main sewerage lines.

You will immediately know if the pipe is blocked. If the bowl is full of water, it will remain there until it can go. Or the water might drain very slowly and indicate a partial obstruction to the waste pipe.

First, use a toilet plunger. The toilet plunger will stir the water to break up any obstructions in the outflow. Toilet plungers are slightly different because they have a flange extension at their ends which makes them more efficient.

You can also try a toilet snake, which is specially designed to remove toilet waste pipes clogs. They are equipped with a long, coil cable that can reach deep to break up the clog.

Clogged flush hole in the jet

The jet flush hole, also known as a siphon jet or a space for holding water, is where the water flows at an angle to discharge waste to the trap. It can become clogged with calcium deposits and other substances over time. As a result, the flushing power decreases.

You can clear the blockage with a toilet cleaner and a brush that can reach the opening. The best way to clear the blockage is to twist the brush and scrub it.

Plumbing Vent System Problems

Like all household systems, plumbing requires a venting system in order to work properly. The vent system regulates the air pressure by moving water through pipes. It also removes gas and other odors from the home.

Problems with the plumbing vent system can affect drainage, water pressure, and flushing. You can then tell if this is happening by the gurgling sound coming from the drains and slow drainage.

This requires professional assistance. This is something that you cannot resolve on your own.

The flapper valve is too loose

To get a good flush, you will need to hold down the flush handle for a while.

The flapper is a valve that lifts water out of the tank and into the bowl. The rod and chain attach it to the flush handle.

If the chain is too long, the flapper will close faster than it should. This can lead to a partial flush.

You can shorten the chain. To shorten the chain, most chains have a clip that you can clip onto another link. If you don’t have such an arrangement, then cut the chain to the right length.

Too low water level

The flushing system will malfunction if the toilet bowl’s water level is too low. If the water level in the toilet tank appears normal, but the water level in the bowl seems low, it is likely that there is a fill valve device in the tank.

Water will leak if the fill valve cracks. This is due to a drop in pressure in the tube that fills up the bowl.

You can determine the leak in the fill valve by removing the top cover and flushing the tank several times. Leakage can be identified if water is seen squirting from the fill valve. Sometimes, the reason for low water levels in the bowl can be hard to determine. So, you will need a plumber.

You will need to replace the fill valve if it is the problem. This can be a difficult task, especially if it is your first time.

Maintain Low-Flow Toilets Tips

It is frustrating and tiresome to have a weak flushing system. These tips can help maintain a low-flow toilet.

  • Let the hot water sit in the bowl for a few minutes. Hot water will dissolve any debris or clogs in the waste pipe. Then, use the toilet cleaner solvent to clean up.
  • The tank’s top is covered by an upright overflow pipe. Put dishwashing detergent into the pipe. Let it sit for 10 minutes before you clean the pipe.
  • Hydrochloric and muriatic acids are used for cleaning the toilets. When dealing with acidic solvents, gloves, eye protection gear, and masks are recommended. If you don’t have overalls, your hands should be protected.

Frequently Asked Questions for Low-Flow Toilets

Do low-flow toilets clog faster?

Not necessarily. There are several factors that can increase the likelihood of a clog. So, ultra-soft toilet paper is best avoided as it absorbs water and doesn’t get flushed away. Also, don’t put tampons or paper towels in the toilet bowl. You can dispose of them in the trash can. You can also do regular preventive cleaning at all times.

Can you adjust low-flow toilets?

The fill valve’s top is fitted with an adjustment screw. To raise the water level, turn the screw clockwise.

How do you know if your toilet is low flow?

Look for the flush volume stamp located between the tank and the seat by lowering the lid. The current low-flow toilet is one that has a stamp of 1.6 GPF (or 1.28 GPF). You can manually calculate the volume if there aren’t any markings. The dimensions of the tank and the flush level are very important. The water used to flush the toilet can be calculated. A low-flow toilet is one that uses less than 1.6 gallons of water.

Can low-flush toilets lead to sewer problems?

They can. Low flow toilets can cause sewerage back-ups in areas with high concentrations. Also, low-flow toilets can cause sewerage clogs.

Wrap it up

Low flush toilets may be an excellent idea for conservation. Low-flow toilets can also cause problems. The new tanks are equipped with compressed air. Thus, increasing the pressure and allowing for better cleaning.

This article will cover all aspects of how to fix a low-flow toilet. It also gives an overview of the layout of a tank and bowl. We also included safety tips and we hope that you will follow them to avoid any nasty accidents.

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