How to Convert a Low-Flow Toilet to a High-Flow Toilet?

Low-flow toilets are quickly becoming a popular choice because they can reduce your home water bill. However, many people feel like low-flow toilets just do not have the requisite flushing power to be effective. As such, they can actually lead to more water usage if it takes multiple flushes to get everything down. 

So, many people are curious:  Can you convert a low-flow toilet into a high-flow one? We will talk about how to convert your low-flow toilet into a high-flow toilet as well as the pros and cons of doing so. Let’s get to it. 

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Low-Flow Toilet vs High-Flow Toilet Differences

First, let’s talk about the main differences between low-flow and high-flow toilets. As the name implies, low-flow toilets use less water than high-flow toilets. A typical low-flow toilet uses about 1.6 gallons per flush. This 1.6-gallon limit is defined by federal law that restricts how much water low-flow toilets can use. 

A typical older toilet uses 6-7 gallons per flush. That is quite a reduction in water use, so you can see why low-flow toilets are a popular method of reducing your water bill. 

Aside from the amount of water used, low-flow toilets differ from high-flow toilets in their design and construction. The outlet on a low-flow toilet is usually located closer to the bottom of the bowl rather than the back. This location allows gravity to do most of the work during flushing so that less water is used. 

Also, low-flow toilets have a different water line that is located closer to the front of the bowl. This causes more of the bowl to be submerged in the water. Lastly, low-flow toilets typically have a larger flush valve than high-flow toilets. The larger valve means that water can flow much more quickly and remove waste. 

We should also specify that there is no official standard for what makes a “high-flow” toilet. Usually, the term just refers to any toilet that uses more than 3.5 gallons per flush. Based on the amount of water they use, some high-flow toilets sit on the lower end of the water-flow spectrum while others stand on the higher end. 

Converting a Low-Flow Toilet into a High-Flow Toilet

Strictly speaking, it is not possible to convert a low-flow toilet into a genuine high-flow toilet. This is because low-flow toilets are designed to use a specific amount of water, and you can’t change this limit without essentially rebuilding the toilet from the inside out.

However, there are several things you can do to increase the flow of your low-flow toilet to make it more efficient to use. Here are a couple of relatively easy DIY methods for improving your toilet flow. 

Check for Clogs

The first and most obvious thing to do is check for clogs. If your low-flow toilet is struggling to clear waste, then some valve or pipe might be clogged. 

The simplest way to fix a clog is to pour a gallon of water into the bowl and flush. The extra water should be enough to force any clogs through the pipes and return the toilet to normal flow.

If pouring water into the bowl and flushing does not work, then you might have a more sturdy clog. The best way to deal with tougher clogs is to use a toilet snake. This handy tool can get up in the pipes past the u-bend to break up any clogs or build-up.

All you have to do is take the snake, insert it into the drain at the bottom of the bowl, and push until you feel the blockage. Then, turn the auger back and forth while pushing to break up the clog. You should be able to tell when the clog loosens because the auger should punch through. 

Check the Water Level

If the snake doesn’t work, then the problem might be that your water level is too low. If the water level is too low, there will not be enough water to clean out waste when you flush. Your tank should have min/max lines on the inside to indicate the appropriate water level. 

If your water level is too low, then you will need to adjust your float. The float (also called the ballcock valve) is the mechanism that tells the tank to stop refilling with water after a flush. You can adjust the length of the level attached to the float valve so that it allows more water into the tank before shutting off. 

If your water level is low, adjust the float until the water level sits comfortably between the min/max lines. If that still does not solve the problem, then move on to the next method on our list. 

Clean the Rim Jets

The rim jets are the small holes that line the underside of the rim of the bowl. The rim jets are the mechanism that allows the tank to put water into the bowl. Over time, rim jets can become clogged with mineral deposits, scum, mold, and slime, resulting in less water coming through and reducing toilet flow. 

The best way to clean the rim jets is to go in with a thin wire and scrape them clean. You can use any kind of thin wire, but we found that a coat hanger works the best because you can bend it and get up in the holes. It might also help if you have a small hand mirror, so you can see exactly what you are scraping. 

Using the wire, reach up into the rim jets and scrape the exterior and interior rims of the jet. If they are clogged, you should start to see gunk come out on the tip of the wire. Once the jets are thoroughly clean, go over them with some toilet bowl cleaner and a rough scrubbing pad. This will get rid of any smaller residue that the wire did not reach. 

Use Bleach

If mechanically removing clogs and build-up did not work, then it might be time to turn to chemical solutions. Bleach is effective for clearing toilets as it can dissolve several types of organic and inorganic build-up like calcium and scum. However, if you do use bleach, make sure that you water it down first. Concentrated bleach is an effective cleaning agent, but it can be very harsh on the internal components of your toilet. We recommend using a mixture that is 2 parts water, 1 part bleach. 

First, turn off the water flow to the toilet. You can do this by turning the water shutoff valve counterclockwise. Once the water has been shut off, pour a gallon of your bleach/water mixture into the bowl. Wait about 20-30 minutes and then flush. Flushing will work the bleach through the guts of the toilet and clear out any build-up you can’t reach with a scraping tool. 

Next, turn the water back on and flush the toilet a few more times to completely cycle the bleach through the pipes. You do not want to leave bleach in your pipes as it can cause problems from corrosion. 

Use Vinegar and Baking Soda

If you do not want to subject your pipes to bleach, then you can use vinegar and baking soda instead. If you remember those volcano school projects, you will know that vinegar and baking soda react to create a fizzy mixture that can dissolve several types of substances, such as the ones that commonly build up in toilets. Vinegar is highly acidic, meaning that it reacts with the basic compounds like limescale and calcium to dissolve them. 

First, take off the rubber fill hose near the top of the tank, making sure that you do not damage it. Next, using a small funnel, pour about a quart of vinegar into the tubes and let it sit for a bit. Then, you can slowly add baking soda until it makes a nice, frothy, fizzy mixture. You will actually hear a small “hissing” sound when the chemicals interact. Make sure you do not put too much baking soda in at once, or you might get an explosion of fizzy mixture in your face. 

Once you have added enough baking soda, let it sit for about 2-3 hours. You can also leave it overnight if you want an even deeper cleanse. Hook the water flow tube back up into the tank and flush the toilet about 3-4 times to work the mixture through the pipes and out into the drain. If your toilet still has flow problems, you can reapply your vinegar and baking soda mixture and see if that makes any difference. 

Check the Flush Valve

The flush valve is located right in the middle of the bottom of the tank. The flush valve is the flap that opens when you flush and closes when the water has been forced through the bowl. If you are having flow problems with your toilet, then the flush valve could be the problem. Over time, flush valves can degrade or become deformed, causing them to leak water into the bowl even when you are not flushing. This results in reduced water pressure when you do flush, clearing waste less efficiently. 

Here is how you can check to see if the flush valve is the problem: the simplest method is to add a few drops of food coloring to the water in the tank. If you see the water in the toilet bowl start to change color, then that means your flush valve is not creating a watertight seal and is leaking. 

If you notice your flush valve is faulty, you might need to inspect it and possibly replace it. First, turn the water main off by turning the knob counterclockwise. Then, flush the toilet to remove water from the tank and bowl. Use a towel or sponge to mop up any excess water still left in the bowl. 

From there, you can remove the flush valve and visually inspect if for deformities, cracks, or holes. If you are lucky, all you will need to do is push the ring back into place so that it creates a proper seal. If the flush valve has holes or cracks in it, then you will need to get a new one. You can normally find flush valves at your local hardware store. Make sure that you take your current flush valve so that you can find an identical replacement that will fit your toilet. Flush valves are pretty cheap and replacing them is simple, so you shouldn’t need to hire a professional plumber for the job. 

Consider a New Toilet

If you have tried all of these solutions and your toilet flow is still off, then you may want to consider buying a new toilet. This is the least ideal solution as a new toilet can be expensive to buy and install. 

If you do opt to buy a new toilet, make sure that the water tank is larger than your current toilet. Ultimately, a larger water tank allows more water, which increases your flow power. 


To sum up everything we covered, there is no way to turn a low-flow toilet into a genuine high-flow toilet, but there are several things you can do to increase your toilet flow. The most common methods involve removing clogs from the pipes and increasing the amount of water your tank lets in. Ultimately though, there will be an upper limit to how much flow you can get. This is because low-flow toilets are specifically designed to use a certain amount of water. 

So, if you have tried all the methods we have listed but still find your toilet flow lacking, then consider shopping around for a new one. A new toilet can improve your flow and make flushing much more efficient.

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