Changing the toilet cistern is less tedious than one might think. Cisterns can leak, stop flushing well or just age, and when that happens, replacement is often the best solution. Whether you have a standard close-coupled cistern or one built into the wall, this step-by-step guide will show you how to replace it yourself and save time and money.
What Is a Toilet Cistern?
A cistern or toilet flush tank stores water for flushing the toilet. It is almost always fixed at the back of the toilet, but in many bathrooms, it may be recessed for aesthetic reasons.
All of the various types of cisterns operate under the same general idea, to hold water and release it when the button is pressed or the handle is pulled. Over time, wear and tear of the parts inside, or a crack in the tank would necessitate its replacement.
Ruhe offers durable, well-built, and reliably performing cisterns, making them a good option if you’re replacing your current cistern.
Signs Your Cistern Needs Replacing
Before you start replacing your flush tank WC, check whether a repair could solve the issue. Sometimes, you might only need to swap out the flush valve, inlet valve, or washer. However, full replacement is needed if you notice:
- Cracks or leaks in the flush tank.
- Constant water running into the bowl despite repairs.
- Rusted or damaged metal fittings.
- An outdated concealed flush tank that no longer functions properly.
- Difficulty sourcing replacement parts for an old hidden flush tank model.
If your cistern shows any of these signs, maybe it is time to replace it.
Tools and Materials You’ll Need
Before getting started, gather the following tools and parts:
- Adjustable spanner or wrench
- Screwdriver set
- New toilet cistern (make sure it matches your flush tank wc type)
- Washers and seals (usually included with the new cistern)
- PTFE tape (for sealing joints)
- Bucket and sponge (for any leftover water)
- Towels or cloths (to protect the floor)
If you’re working with a concealed flush tank or a hidden flush tank, you may also need to access the wall panel or remove tiles, depending on your bathroom setup.
Step-by-Step Guide to Replacing a Toilet Cistern
1. Turn Off the Water Supply
Turn the cistern’s water supply off. This causes water to stop from entering the cistern while you work.
2. Drain the Flush Tank
Drain the flush tank by flushing the water inside. Soak the remaining water at the bottom with a sponge or towel.
3. Disconnect the Water Inlet
Using your wrench, loosen the nut that connects the water inlet hose to the bottom of the cistern. Keep a bucket handy to catch any drips.
4. Remove the Old Cistern
Unscrew the bolts that secure the cistern to the toilet pan. Lift it off carefully and set it aside.
5. Prepare the New Cistern
Follow the manufacturer’s instructions to assemble the flush mechanism inside the new toilet flush tank. Apply plumber’s tape to threaded parts to help prevent leaks.
6. Position and Fix the New Cistern
Place the new cistern onto the toilet pan, aligning the holes with each other. Bolt through the holes with washers and tighten only to hold the cistern steady, overtightening may crack the ceramics. If one is interested in replacement, Ruhe cisterns are easily available and fit most toilet pans, thus allowing for easy DIY installation.
7. Reconnect the Water Supply
Attach the water inlet hose to the new cistern’s fitting and tighten it with the wrench.
8. Refill and Test
Turn the water supply back on. Allow the cistern to fill, then press the flush button or lever. Check that the flush is strong and that there are no leaks around the inlet, outlet, or bolt areas.
How to Repair or Replace a Concealed Flush Tank
Replacing or repairing a concealed flush tank can be a bit challenging since it’s built inside the wall or behind a panel. For major issues, like a cracked or leaking tank, it’s best to call a plumber. But for minor repairs, you can usually fix things yourself through the flush plate opening, without removing any tiles.
Here’s how you can do it:
1. Turn Off the Water Supply
Locate the shut-off valve (usually behind the flush plate or near the toilet) and turn it clockwise to stop the water flow.
2. Drain the Tank
Press and hold the flush button to empty any remaining water from the cistern.
3. Remove the Flush Plate
Gently take off the flush plate. Most plates are clip-on or spring-loaded, revealing the service opening for access to the tank’s internal parts.
4. Disconnect the Internal Components
- Detach the flexible inlet hose from the cistern.
- Unscrew the flushing rods or buttons by turning them anti-clockwise.
- If there’s a debris plate, remove it to expose the siphon and float valve.
- Carefully lift or twist out the siphon and float valve — they usually unclip easily.
5. Clean or Replace the Parts
- Wipe away any limescale or dirt using a cloth or descaling fluid.
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Replace any damaged parts, making sure they’re compatible with your cistern model.
6. Reassemble the System
- Refit the siphon and float valve securely.
- Reconnect the flush rods, flexible hose, and debris plate.
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Make sure everything clicks or locks firmly in place.
7. Restore Water and Test
Turn the water supply back on slowly, check for leaks, and test the flush mechanism a few times. Once everything works properly, reattach the flush plate.
When to Call a Professional:
If the tank is leaking inside the wall, built directly into tiles, or if you’re unsure about dismantling the system, it’s best to get professional help. Plumbers have the right tools and expertise to handle concealed installations safely.
Pro Tip: Most concealed tanks are designed for easy maintenance through the flush plate, so full replacement is rarely needed. A quick part swap often solves the issue without breaking tiles or walls!
Extra Tips for a Smooth Installation
- Pick a cistern that matches your toilet model.
- Always use new seals and washers.
- Check with a spirit level to keep it straight.
- Flush a few times to make sure it works.
While installing, keep a check so that the tank does not leak within the first 24 hours. Clean the tank frequently and check the seals every couple of months.
For fewer replacements in the long run, go for the high-quality flush tanks like Ruhe cisterns with good build and easy installation. Also, while cleaning, never use chemical cleaners inside the tank as they could cause damage to seals and fittings.
You May Also Like to Read:
Understanding Different Types of Urinals for Modern Bathrooms
Installing a toilet cistern doesn’t have to be difficult. With the right tools, a bit of care, and a reliable model like Ruhe’s cisterns, you can get your toilet back in perfect working order in no time. For more complex setups like concealed tanks, it’s always wise to call a professional. With regular maintenance, your toilet will stay efficient and trouble-free for years.
