If you talk to any plumber, they will tell you that they either don’t want to work on an in-wall toilet cistern or simply just don’t know how to. The introduction of the in-wall toilet cistern came about 15 years ago to the plumbing market in Adelaide and has gradually gained momentum and we are seeing more of them installed over the years.

wall cistern


The advantages are quite simple and straight forward for installing these into a wall cavity:

  • Saving of space inside the room by having the toilets cistern concealed into the wall cavity.
  • Not having to see this fixture which in turn creates a more aesthetically appealing space.
  • For hygiene purposes you might find people opting for these to be installed inside the wall.
  • Public spaces many businesses such as night clubs and hotels will have these installed to protect the toilets cistern from vandalism.


The disadvantages from an owner’s perspective are very little except for the costs of having repairs done. The labour can be very extensive and the genuine parts which are required are very hefty.

How are the repairs performed?

1. The first trick is to carefully have the front button panel removed. Grohe havedesigned a unique spring-loaded clip whereby carefully pushing the entire flush panel to the right it will allow the right-hand side to pop off enabling the left-hand side to gently release. This is a trick many plumbers don’t understand and will cause unnecessary damaged before the repairs have even commenced, not a great look in
front of the customer!

2. Once the button plate has been removed it is important to take care of the flushhoses. Unlike other manufacturers Grohe have made their flush hoses very small in diameter and very soft so care needs to be taken when disassembling as a punctured air hose will mean the flushing mechanism will not operate once repaired.

3. Now there is some sort of access to the internal operations of the cistern its where the fun begins if you can call it that. Firstly, make sure the water is isolated (as you will see in the photo on this page) majority of installations will have isolation valve. Turn the water off.

4. To have the inlet valve taken apart it will require you to disconnect the water hose from the isolation valve and the inlet valve. Once the hose is disconnected and removed it is quite easy to unclip the inlet valve being held in place by 2 x C style plastic clips part of a dark grey mould. Once the inlet valve is loose you will need to remove the top part of the of the outlet valve (this also makes up the overflow tube) by simply twisting it and this will come loose allowing you to lift it out. By having this extra space inside the cistern, it will allow to manoeuvre the inlet valve out carefully (as seen in picture on this page).

5. If you also need to have the outlet assembly repaired most of the work is done. What needs to happen is the outlet valve needs a firm twist as low down as possible and it will release allowing you to also lift this out and perform repairs or replace completely (outlet valve assembly in picture on page).

6. Once the repairs have been made or new parts ordered in it’s a matter of performing all the above tasks in reverse. One-point worth noting is that the foam float valve on the water inlet valve should be adjusted (by turning it anti clockwise) to a little over halfway up the adjustment chamber in order to get the correct water level inside the cistern once put back together. We always find the addition of some silicon grease to the rubber’s seals (on the flush rubber chamber seal which comes apart in half forming the internal overflow tube and the rubber seals on the inlet hose’s female nuts assist with installation and sealing).

The Grohe in-wall toilet cisterns are a very nice high-end piece of equipment and make a fantastic addition to any home or business. The catch will always be finding a plumbing contractor who can work on these toilet cisterns and successfully repair them with the minimal of fuss and without breaking something. Mayfair Plumbing and Gasfitting have been helping hundreds of homes and businesses since the introduction of these products into the plumbing market and we carry most of the more common parts as van stock to have your in-wall toilet cistern repaired the same day across Adelaide and the Adelaide Hills of South Australia.

grohe cistern and valve
a toilet flush button
a water valve on a wall

Aaron Stewart

Aaron Stewart is the found and owner operated of Mayfair Plumbing & Gasfitting based in Adelaide, South Australia.

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