Are Toilet Tanks Interchangeable?

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If your toilet is no longer functioning, you may be asking yourself whether or not you can replace just the tank. Are toilet tanks interchangeable? 

This is a fairly common question, actually. And the answer is that in most cases, they unfortunately aren’t. 

However, there are exceptions. 

In my ten plus years of experience as a rental property manager, I’ve come across just about every toilet brand in the market. 

And what I can state is that, when it comes to replacing a toilet tank, it’s always best to start with the manufacturer of the toilet. Trying to match a toilet tank from a different brand is sort of like trying to fit a Honda engine in a Chevrolet-made vehicle… it just won’t work. 

Now, in rare cases, there may be a similar model that you can match the tank to. But more often than not, you’ll simply need to purchase a new toilet.

So, what happens if the tank suddenly stops working? Can you simply replace this individual part? 

Types of Toilet Tanks

There are three main tanks used in most American homes. They are gravity, dual flush, and pressure-assisted tanks. 

What makes these tanks so popular is their ease of use, affordability, and overall efficiency.

Gravity Tanks

Gravity toilet tanks are typically best sellers, and they’re also one of the oldest flushing systems still used today. They use gravity to create flushing pressure when the lever on the toilet is pressed. 

When the toilet is flushed, a siphoning action is created that forces the contents from the toilet tank and bowl down the trapway. 

I generally prefer gravity toilets because you can find their replacement parts rather easily. You may also have a higher chance of finding a similar model (from the same brand) to fit if you need to replace the tank.

Dual Flush Tanks

Dual flush tanks are a bit newer than gravity toilet tanks. They have a fairly similar design, the biggest difference between the two being that the dual flush tank has two buttons on top of the tank — one for solid waste and the other for liquid waste. 

This dual flushing system allows you to reduce the amount of water used when the toilet is flushed, resulting in a lower water bill. Finding replacement parts may not be difficult. 

However, it’s fairly unlikely that you will find a complete tank that’s interchangeable. If you do, expect to pay a pretty penny for it, as these tanks are typically more expensive.

Pressure-Assisted Tanks

Next up, you have pressure-assisted toilet tanks. 

This type of tank also uses gravity, but instead of the stored water being pulled down by it into the bowl, an airtight plastic tank pressurizes the water — forcing the water inside the bowl down the sewer line. 

This powerful flushing system is common in the public sector, and you’ll often see it in hospitals, schools, hotels, and office spaces. 

Given that these toilets aren’t as popular with residential buyers as they are with industrial buyers, it may be more challenging to find tank-only options. However, it’s not completely impossible. 

Though, you’ll also typically be able to find replacement tank parts rather easily.

How to Find Out What Kind of Tank You Need

If you’re simply looking to replace your toilet with a similar make and model, just locate the purchase receipt of your current porcelain throne. If you can’t find it, or even your instructional manual, remove the tank lid and take a glance at its bottom. 

You’ll usually find the serial or model number and manufacturer name stamped on there. If the toilet is old, you may need to wipe off the lid a bit to remove some of the grime that can accumulate on it over time. 

If it’s not there, check the inside of the water tank next, as the model number may be on the side of the tank right beneath the waterline. You may need to use a flashlight to get a better look inside. 

Once you have the make and model of the tank, you can find other tanks with similar flushing systems and measurements. 

However, if you had your toilet customized specifically for your home, it’s best to reach out to the manufacturer to find a similar model, order a new one, or order replacement parts.

How to Measure the Toilet Tank

Measurements are crucial when it comes to placing your toilet’s tank. These will consist of the depth, length, and width of the toilet. 

To measure your toilet, grab a measuring tape and measure the length from the lid to the bottom of the tank. The average toilet tank lid is about 1 and 1/2 to 2 inches tall. 

Next, measure the distance from the front of the lid to the back of it. 

Finally, measure the width from the left side of the tank to the right. 

Often, you’ll find that manufacturers will offer various tank sizes of different models to make buying a replacement a pretty simple process. 

If you’re unsure about the toilet tank size, grab the model number and visit your local home improvement store — they can guide you on the appropriate options. 

You’ll also want to measure some of the major components inside of the toilet tank. This includes the length of the refill tube, the height and girth of the overflow pipe, and the height of the fill valve. 

The fill valve is typically the tallest component in the toilet tank, and if the new one doesn’t fit you won’t be able to place the tank lid on completely. 

Lastly, there’s the flush valve (aka “the flapper”). There are different sizes for these, and their diameter will depend on that of the flush hole. However, you’ll find that this piece is typically interchangeable between toilets, especially if it comes as part of an assembly within a flush valve kit. 

Most flappers will be labeled as either a 2-inch or 3-inch flapper.

Can You Buy a Toilet Tank From a Different Manufacturer?

This is a fairly common question, and the answer is usually no. 

It’s best to stick with the same manufacturer of your current toilet if you’re buying the replacement tank on its own. Though a toilet tank may look similar on the outside, and in some cases, even on the inside, it’s unlikely to perfectly match up. 

The truth is that each toilet brand has specific components and building processes that they use to manufacture their toilets.

If you try to replace the tank with a different brand, you may find yourself spinning your wheels trying to understand why the new tank isn’t fitting or working properly after you install it. 

But what if my current toilet model is old and obsolete, you ask? 

Luckily, manufacturers consider this when developing new models and will usually have an option that can work. If they don’t, chances are they’ll simply recommend replacing the toilet entirely (meaning the tank and the bowl). 

Hey, we can’t win every battle, right?

Are the Tank Bolt Sizes Standard?

Yes and no. Similar to how toilet tanks vary, the bolt sizes will vary as well. 

However, you’ll find that toilets that are similar in size will usually have the same sized bolts — the most common bolt sizes for most toilets being 1/4 inch and 5/16 inch in diameter. 

The best way to ensure that you get the right sized bolt replacement for your toilet is to remove one of its current bolts and take it to the store with you when purchasing a new one. 

If you’re making the purchase online, you can measure the diameter of the bolt head and thread length to buy a replacement. But, if you really want to make things easier for yourself, simply look up the specs of your current toilet online or in your user’s manual. 

Either one of these should include the current bolt sizes for your toilet. Or you could always reach out to the manufacturer.

How to Replace a Toilet Tank

Installing or replacing a toilet tank is fairly straightforward. The most important thing to remember is to avoid over-tightening the bolts — which can cause serious issues.

Start by turning off the water supply with the water valve behind the toilet. Next, remove the old tank lid and set it to the side. Then, take an adjustable wrench and loosen the nuts and bolts that fasten the tank to the toilet bowl. 

After removing these bolts, you should be able to gently lift the tank from the bowl. Keep in mind that these tanks are fairly heavy, so you may need an extra set of hands for safety.

Take the rubber gasket assembly and install it at the bottom opening of the new tank. Some may already have it pre-installed.

Next, set the new tank on the bowl and line it up with the bolt holes.

Place the nuts, washers, and bolts onto the tank and tighten them with your adjustable wrench. 

Make sure you don’t over-tighten the bolts! You can crack the toilet tank and the bowl, and this can cause leaks and potential water damage to your bathroom.

Once the tank is secured, turn the water valve back on and flush the toilet to test its functionality. 

Double check around the toilet tank and bowl to ensure that there are no leaks. If everything looks ok, you’re good to go!

Summing Things Up

As you can see, there are quite a few things to consider before replacing your toilet tank. 

The most important thing to remember is this: get the make and model of your current toilet tank, and take measurements to determine whether you should buy a replacement tank — or a completely new toilet

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