Are Toilet Tanks Universal & Interchangeable? (Answered)

Toilets are undoubtedly one of the most important components of our homes. They are a crucial piece of our daily hygiene and provide us with a way for proper sanitation and safe disposal of urine and feces.

Toilets often require necessary maintenance, about which you can learn below along with other relevant information.

Are toilet tanks universal & interchangeable?

Toilet tanks are neither universal nor interchangeable since they are meant to be fitted on specific toilet models. Although there are several brands that provide interchangeable toilet tanks, you must know the measurements, toilet type, tank size, and model number before getting a replacement. 

Toilet tanks are vulnerable to many issues, whether it be leaks, damaged fill valve or be it faulty vents – replacements become a necessity.

While you might think of replacing a tank, it is critical to note that most toilet tanks are not interchangeable. Therefore, It is recommended that you buy a replacement tank that exactly matches your tank model.

You should initially note the brand of your toilet, the most common and leading toilet brands are Kohler, American standards, Aquasource, Fluidmaster, Glacier Bay and Sterling among others.

Even within the same brand, it is not assured that a tank of any model would perfectly fit your specific tank model.

Therefore, it is suggested that you contact your tank brand’s manufacturer to inquire about interchangeability or perhaps you can seek professional help from a plumber instead.

In general: Aquasource models are not interchangeable, Few models of American standards are interchangeable and several Kohler and Fluidmaster tanks are interchangeable.

What are the different types of toilet tanks?

Toilets tanks come in varying shapes and sizes according to the type of toilets they are fitted to. Toilets are classified based on their functioning mechanism, you need to understand your toilet type before you buy a replacement

Dual Flush Toilet Tanks:

Dual Flush Toilet Tanks consist of two joint buttons located at the top of the tank. The two buttons use different amounts of water to flush – one for solid waste, while the other for liquid waste.

Dual Flushes allows you to save on water bills by allowing you to control the usage of water.

If you have a dual flush toilet, make sure your replacement tank is compatible. Although many dual flush toilets allow tank replacement, some models require a complete installation if the tank is faulty. So, consult with a plumber or an employee of your toilet brand before buying.

Gravity Toilet Tanks:

Gravity Toilet Tanks are the most common flushing systems used in homes. These systems use gravity to release water under high pressure from the tank and flow to the toilet bowl, siphoning the waste down the sewage.

These tanks are the easiest to fix and their replacement parts are easy to find due to its popularity. Therefore, there is a high chance of finding a compatible replacement of your tank model or a similar model from the same brand.

Pressure Assisted Toilet Tanks:

Pressure-Assisted Toilet Tanks flush down water under high pressure using a special mechanism built into the tank. They work similar to gravity toilet tanks but with much more efficiency.

Despite their effectiveness, these expensive flushing systems are mostly used in public spaces such as hotels, offices and hospitals.

Apart from their costliness, the critical issue with this type of tank is its unavailability of replacements. Although it is easier to find replacement parts for the mechanisms of the tank, it’s improbable to find a tank replacement.

How do you know what size toilet tank to buy?

Having the purchase receipt or instruction manual of your toilet can help you know the model and serial number. But if you have lost it, you can manually find the model and serial number below the tank lid.

Most tanks have the brand name, serial number or model numbers beneath the tank lid, or behind the bowl. You can learn the model number from the employees of a bathroom supplies store if you know the serial number and brand name – allowing them to find a compatible replacement tank for your toilet.

How do I measure for a replacement toilet tank?

Toilet Tanks do have specific standard dimensions compatible with all toilets. Therefore, it is heavily advised to always measure your tank for a perfectly fitting replacement tank. The directions for measuring your toilet tank is laid down below:

Measure your toilet tank’s dimensions:

You are required to take three necessary measurements of the tank: Length, Depth and Width. Measurements for length and width can be done just from the lid of the tank. Ideally you should take off the lid and take the measurements from its bottom.

Measure length from front the edge extending to the back and width from one side of the lid to the other. Next, put on the lid and measure depth from the top of the lid down to the tank base.

Measure the pipes and valves:

Once you’re done with tank measurements, proceed to measure the pipes and valves. Firstly, measure the flush valve gasket’s diameter located underneath your tank.

Next, measure the length of the supply tube and overflow pipe along with the diameter of the fill valve. The supply tube will be fitted to the fill valve, so be cautious with their measurements.

Measure the nuts, bolts, and washers:

Nuts, bolts, and washers are essential for a leakage-free installation, therefore take note of the diameter of the nuts or if possible, take one with you for reference.

How to install a toilet tank?

Replacing your toilet tank should be fairly simple if you carefully follow the steps below:

Take off the old tank:

Turn off the water supply and flush the tank empty. Next, unscrew the supply pipe from the fill valve.

Afterward, unhook the tank from the bowl by unscrewing the bolts and washers from underneath the toilet bowl. The tank should come off the bowl if rocked gently and lifted.

Set up the new tank:

First, install the flush valve gasket that came with the tank. Next, screw the bolts at the bottom of the tank by placing a washer and a bolt from the inside of the tank and then place another washer on the outside and screw them with a nut.

For a tighter seal, you can place some Plumber’s Putty between the bolt and the washer.

Afterward, align the bolts with the holes and place the tank on top of the bowl. Upon placement, screw the bolts tight from underneath the bowl with washers and nuts.

Finally, plug in the supply pipe to the fill valve while holding the fill valve for a tight installation.

Trial flushes:

As the installation is complete, turn on the water supply and flush several times to make sure the tank functions properly. Also, observe if any leaks happen between the tank and the bowl gap.

How do you know if a toilet tank is compatible?

The rule of thumb is that toilet tanks apart from the same brand and model are incompatible. Therefore, you should get a replacement tank of the same brand and model.

Many toilet tanks are visually identical on both the outside and the inside, but even the tiniest difference such as bolt placement could render a replacement tank incompatible.

However, many manufacturers design their new models to be compatible with their older ones. This gives you an option to avoid completely replacing your old toilets and simply replace the tank.

If all the bolts and parts match, then they are compatible.

Are Toilet Tank Bolt Sizes Standard?

Just like toilet tanks bolt sizes are not standard, however, there are bolt sizes that are commonly used for toilet tanks. Bolts of ¼″ and 5/16″ diameter are the most common sizes for tanks.

Still, you should check for the size of bolts used in your tank.

You can ensure the bolt size by removing an old bolt and taking it to the store for reference. An alternative to this could be to measure the diameter of the bolt head and length of the bolt.

Are toilet tank levers universal?

Toilet tanks often come with levers instead of buttons. Unlike buttons, levers come in various shapes and sizes which poses incompatibility in toilet tanks during replacement.

The 5 types of levers commonly used are Front Mount Handle, Side Mount Handle, Angle Mount Handle, Extended Long Reach Cistern Lever Handle and the Universal Toilet Lever. 

Apart from Universal Toilet Levers, all of the levers come preinstalled with the tank and are not universal. However, the Universal Toilet Levers are built to be used universally and are ideal levers to be used as a replacement.

Final Thoughts

Toilet tanks are not universal nor interchangeable and are often unique to specific toilet models. Interchangeable toilet tanks are available for several brands but you must know their specific dimensions, tank type, tank size and model number for a compatible replacement.