You may sit on the bowl itself, but without the cistern – the tank that holds the water ready to flush – it’s not going to be a very satisfying experience! If it’s time to replace toilet cistern due to it being cracked, otherwise significantly damaged or it’s just time for a modern upgrade, a full replacement is something that isn’t too tricky to do.

Is replacing toilet cistern even legal?

First, a warning: In NSW, like most other jurisdictions across Australia, plumbing codes will require you to hold a valid plumber’s license for any significant plumbing work other than changing a washer, swapping out a showerhead or fitting a comfy new toilet seat. This includes the replacement of a toilet cistern only. So check with your local authorities before you repair or replace a toilet.

What may surprise you, however, is that while it’s the critical component of the hardest-working seat in your home, replacing the cistern actually isn’t too hard if you have the confidence and basic skills. How to change a cistern?

First, you’ll need:

  • New cistern (including bolts)
  • Adjustable wrench
  • Screwdrivers
  • Sponge, towels & bucket
  • Plumber’s tape
  • Rubber gaskets & sealant.

How to replace a toilet cistern in 7 simple steps

Step 1: Prepare

Turn off the water supply both at the mains and at the valve located behind or next to the toilet itself. Now flush the toilet to get rid of the stored water in the cistern, and use the sponge and bucket to get the last races out too before you replace cistern.

Step 2: Disconnect the water supply

At the bottom of the cistern, you’ll find the water supply line. Remove it with the wrench and be ready for the release of a little more water with the bucket and towels.

Step 3: Remove the old cistern

It’s done by unscrewing the nuts that attach the cistern to the bowl – find them at the bottom of the tank. If they’re corroded or stuck, try using some penetrating lubricant before trying again. Once they’re off, just lift the cistern off the bowl.

Step 4: Prepare the new cistern

Hopefully you’ve already ensured the replacement toilet cistern is compatible with your existing bowl and toilet configuration, so unpack it and follow the instructions to see if any mechanisms need to be assembled before you try to install it. Place new rubber gaskets on the new cistern bolts so you’ll have a nice, watertight seal.

Step 5: Position the new cistern

The new cistern and the top of the toilet bowl should perfectly align with the mounting holes so that you can easily secure the installation with the nuts. When replacing a cistern, be careful not to over-tighten as it can not only damage the cistern but even crack the porcelain.

Step 6: Re-connect the water supply

Wrap the threads of the inlet valve with Teflon plumber’s tape, which is critical for a tight and permanent seal when replacing the cistern. Now it’s just a matter of re-connecting the water supply line to the bottom of the cistern with the wrench – and remember, don’t over-tighten!

Step 7: Test, seal & you’re done!

Fully restore the water supply, and you’ll know you’ve done it correctly because you’ll hear the cistern start to fill up. Carefully check if the cistern is leaking while this happens, and once you’re sure and the tank is completely full, do a test flush. If everything’s working perfectly, add a bead of sealant around the base of the cistern to ensure it’s all watertight for good. And now pat yourself on the shoulder for a job well done. You’ve learned how to change toilet cistern parts and it all works perfectly!

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Toilet cistern replacement – The easy way!

But don’t forget, fiddly DIY jobs – especially on your home’s critical plumbing functions – aren’t for everyone, because they can turn a minor issue into a big, watery, expensive disaster! And in NSW as well as most other Aussie jurisdictions, work like this can only be carried out by a licensed local plumber – like Rapid Service Plumbing right here in Sydney and beyond.

No matter what TLC your home’s hard-working throne needs, we do it all with obligation-free quotes, $0 call-out, a price match guarantee and fully guaranteed workmanship for life. Give Rapid Service Plumbing a call today – 24/7.