How to Replace a Toilet Tank? A Step-By-Step Guide

Last update:

Toilet tanks are durable, but they can’t last forever. Most tanks have plastic parts, so you’ll probably need to replace them after years of wear and tear.

But how to replace a toilet tank? It’s a simple 10-step process because toilet cisterns are accessible and easy to replace. We’ll show you how to do it.

Tools You’ll Need to Replace a Toilet Tank

Changing the toilet tank requires a set of common household tools. You probably have most of these, but let’s breeze through the checklist:

  • A new tank that matches the dimensions of the old tank
  • A rubber gasket
  • A new pair of tank bolts (optional) and rubber washers
  • A sponge and dry towels
  • An adjustable wrench
  • Pliers and a flathead screwdriver 

How to Replace a Toilet Tank?

Toilet tank replacement is one of the easiest DIY bathroom projects, so it’s suitable even for beginners. Instead of calling a professional plumber, you only need to follow these 10 steps:

Step 1: Close the Shutoff Valve

You need to shut the water off before you start working. First, turn off the shutoff valve – it’s a small knob on the rear wall that usually hides behind the toilet. Alternatively, the valve is right next to the toilet tank.

You can close the supply valve manually by turning the knob clockwise. If the shutoff valve won’t shut off, it is probably too rusty to budge. You need to spray it with penetrating oil such as WD-40 to loosen the metal part.

After that, you can close the valve with your hands.

Step 2: Flush the Toilet and Drain the Tank

After you’ve closed the shutoff valve, flush the toilet and drain the toilet tank. All it takes is to press the flush handle and hold it for a few seconds. This is important for multiple reasons.

Firstly, you don’t want to flood the bathroom floor. Secondly, you want to stay dry while replacing the toilet tank. And thirdly, the tank is much lighter when you empty it – there is no reason to struggle with excess weight. 

Step 3: Disconnect the Water Supply Hose

The water supply hose is a metal tube connecting the tank to the shutoff valve. It is only a few inches long, but it can be surprisingly hard to detach – the threaded nut holding the hose to the tank is often rusty and stiff.

In such circumstances, you can again use penetrating oil like WD-40 to spray the metal nut. It will become loose after a few minutes, so you can unscrew it effortlessly. But beware of leaks as there can be remaining water in the hose.

Step 4: Unscrew Tank Bolts

Toilet tanks usually have two bolts near the bottom – one small screw on both sides of the plastic cistern. Before changing the tank, you have to remove the tank bolts by unscrewing their nuts with an adjustable wrench.

Grab a bolt from outside the tank with locking pliers. After that, open the tank lid to locate the other part of the bolt hiding inside – you’ll notice it next to the long fill valve. Use a flathead screwdriver to unscrew the bolt.

After you remove the bolts, detach the rubber washer from each bolt with your fingers. The rubber washer is thin and tends to stick to the bolts tightly, so it’s better to dispose of old items.

Step 5: Disconnect the Tank from the Toilet Bowl

This is one of the easiest parts of your work. All it takes is to grab the cracked tank from below and lift it – you’ll notice how light an empty tank is. When you detach it, remember to put the tank on a towel as there still may be droplets in it.

Without the toilet tank, you will instantly spot a rubber gasket on top of the toilet bowl. This is another element that you ought to replace, so don’t forget to remove the old gasket. You can do it with a screwdriver or a putty knife.

Step 6: Buy a Tank That Matches the Same Dimensions

Many people forget this detail, but toilet tanks come in different shapes and dimensions. You can’t just browse the Internet and buy a random toilet tank. It’s important to buy a model that matches the existing toilet structure.

Purchasing the same model is an easy solution. If you want to replace it, be careful to find a model that matches the same dimensions.

Besides that, American Standard Cadet Pro is a high-efficiency model with ultra-low consumption. It makes American Standard one of the finest models in the mid-level price range.

Step 7: Replace Old Rubber Washers and the Gasket

It’s a good idea to replace old washers with new ones. Many toilet tanks come without a new pair of rubber washers, so you should buy some to make sure everything fits in properly.

Simply slide each washer over a bolt and turn it with the wrench to put them into place. Make sure the rubber washers stay in place while you tighten the nuts back – that way, you will prevent leaking from tank bolts.

You should do the same with the gasket. Purchase a new rubber gasket and put it on top of the toilet bowl – the gasket creates a tight seal, enabling flawless flushing in your toilet.

Step 8: Install a New Tank

After you replace the washers and the gasket, it’s time to install a new toilet tank. Put it back on top of the bowl with its bottom sitting on the rubber gasket.

The next step is to slide a pair of bolts through bottom holes on both sides of the toilet tank. Grab the adjustable wrench to tighten threaded nuts, all while screwing the bolts with the screwdriver.

When you do that, you must put the cover on top of the toilet tank. The only thing that’s missing now is the water supply.

Step 9: Reinstall the Supply Hose

Your toilet tank is ready for work, but it lacks a water supply. That’s why you have to reinstall the supply hose. Here’s how:

  • Take a metal hose in your hand and press it against the toilet tank
  • It should snap into the fill valve hole on the bottom of the tank
  • When you do it, the next task is to turn the hose nut clockwise – it will secure the water supply line  

Now the supply hosepipe is fully functional, so you only have one more step to take.

Step 10: Open the Shutoff Valve

You probably know how to open the shutoff valve – just turn it counterclockwise to allow water to flow through the supply hose. Make sure to twist the full circle as it will provide your toilet tank with enough pressure to flush powerfully.

Our advice is to open/close the metal valve from time to time, even if you don’t need to fix anything in your bathroom. The reason is simple – turning the knob will keep the valve in good shape, so it can’t get stuck.

The next time you do something around the toilet tank, closing the water supply valve will take you not more than a few seconds.

The Bottom Line

So how to replace a toilet tank? It takes 10 steps to do it, but each one is relatively simple. You don’t need to mess around with small parts like the flush valve – the only task is to detach the old toilet tank from the toilet bowl.

After that, it is only a matter of reassembling the fixture and putting a new toilet tank in its position. Are you ready to give it a try?


Can I replace the toilet tank only?

Yes, you can replace the toilet tank only. Sometimes there is no reason to change toilet bowls, so you can focus on replacing the tank.

For instance, the old toilet tank is not filling with water, and you can’t fix it. In this case, the solution is to replace the toilet tank without changing the toilet bowl and other components.

Are toilet tanks interchangeable?

Most toilet tanks are not interchangeable. You may run into similar types of toilet tanks, but the majority of models are too different to match. It would be bad to buy a random toilet tank and expect it to suit the existing setup.

The best solution is to stick to the same manufacturer as they tend to create similar models with the same dimensions.

Leave a Comment