Repair, fix and maintain Grohe flush system

by Updated: May 4, 2022diy-miscellaneous56 comments

Grohe cistern repair

Fix and maintain Grohe toilet flush system

Grohe dual flush / concealed cistern systems are worldwide known for their quality and reliability. Grohe systems are maintenance free and works for long time without any service.
thumbUP_gifanim Tip: In many countries Grohe warranty is valid for 5-10 years.
You better first check if your warranty is valid and use it prior of following this guide.

After several years of using Grohe system, especially in a high calc level of water (=hard water, = water with high mineral content) and due to material aging, some de-calc, cleaning, maintenance and possibly gasket replacement might be required.
Grohe concealed cistern design is sophisticated and was made so tight that some guidance in needed on how to take it apart in order to perform a cleaning, repair and maintenance process.

When I searched for information on how to repair or take it apart, I have found very little information so I have decided to create my own guide to help you out in the process of taking apart this system. Enjoy it.

DISCLAIMER – Important!

exclaim2 Please note:
* This guide shows the Grohe GD2 system, cat. # 38642 000 but it might also help with other models as well.
** In this guide the float valve location is on the left side. Since Grohe system was designed symmetrically, it can be located on left or right depends on your water supply installation.

The process of repairing / maintaining Grohe flush system involves:

* Don’t worry, it is easy to gain access to Grohe cistern parts. There is no need to break tiles or wall to do so.
Accessing the system is done through the access panel which is found under the actuation panel.

a: Disassemble according to the following guide.
b: Clean parts from calc buildup, dirt, sand / small stones etc.
thumbUP_gifanim Tip: You can gently brush the parts under running water.
To get into hidden places, best and cheap way is to soak parts in a Citric acid solution. (use 1 full teaspoon for every liter of water). Citric acid powder can be purchased in every grocery store. Let it soak for a few hours to remove all calc.
thumbUP_gifanim Tip: When done cleaning and prior to assembling, I advise to test moving parts and make sure it moves freely.
c: Replace any required / fault part.
d: Assemble all parts in reverse order to the disassembly steps.

Main parts of model GD2 that needs to disassemble are:
A. Pneumatic actuation plate
B. Water filling float valve
This sub-assembly consists of 2 main parts and additional parts that needs cleaning.
C. Stabilizing bracket (frame)
D. Pneumatic discharge valve (drop-valve)
This sub-assembly consists of 3 main parts and additional parts that needs cleaning.
Its lower part (the rod) holds the silicone seal that opens the water flow of the flush.
Grohe GD2 main parts – general view
* Image shows assembled parts outside the container
Disassembly process:
exclaim2 Note: Clicking on each image will open a bigger image.
1. Take off the actuation plate.
Push the lower part of the plate a bit up (1) and than rotate its upper part towards front (2) to release it and taking it off.
thumbUP_gifanim Tip: Take it off just a few centimeters as 2 air hoses are connected to it.
2. Turn off water supply.
Use flat screwdriver and turn it CW
3. Push the big knob to discharge all water in the cistern.
4. Disconnect the 2x air hoses that connects to the actuation plate. Just pull it straight.
Place the actuation plate aside and keep its front plate from getting damaged / scratched.
thumbUP_gifanim Tip: Mark the actuation plate so you’ll know which hose connects to each button connector.
4.1. Further disassembly of the actuation plate and pneumatic buttons. This is necessary only if buttons does not function well and if you have the required spare parts (read next)

exclaim2 Note that though this plate consists of several detachable parts that can easily be replaced, Grohe does not sell any of it. You’ll be offered to replace the full subassembly panel which costs a lot. Grohe unfortunately does not care about the environment and sustainability matters when it comes to its own parts.
Just in case you got those parts, here are some disassembly images that might help.

5. Remove front frame. Unscrew 4x screws and pull frame straight. Use Phillips head screwdriver.
6. Disconnect water supply hose.
Turn ring CCW by hand. Move the hose end to the side of the cistern.
7. Disconnect water float valve from the stabilising frame.
First push the latch up (1) and while holding the latch, slide the float valve towards the center (2).
8. Remove the float valve from the cistern.
Do it while turning it along with pulling it out.
8.1. Further disassembly and cleaning of the float valve
9. Remove stabilising frame.
First squeeze both latches (1) and than pull the frame upwards (2).
10. Remove the pneumatic discharge valve from the cistern.
Separate it to 3 parts while inside the cistern.
exclaim2 Note: Correct orientation of the Blue cap in image 10.d. should be turned by 180 degrees, as seen in image 10.a.
10.1. Further disassembly and cleaning of the pneumatic discharge valve

11. Seal gasket.
Located at the end of the rod.
If Silicone seal needs to be replaced, this is where you’ll find it.

12. thumbUP_gifanim Tip: Clean the cistern container.
If you have got that far, it is advised to clean the bottom of the cistern container. Insert your hand into the container and pick any stones, sand etc. found in its bottom. You can turn on water supply and use running water to move and flush any debris found in the container bottom.
Since water goes from the container to the toilet, it is best to take out any large particles by hand to avoid jamming of the toilet water diffuser holes.

Assembling steps:

  1. Insert the seal rod to the cistern. (seal facing down)
  2. Insert the pneumatic subassembly to the cistern and insert the rod inside it using its slides.
  3. Place the Blue cap on top of the rod (6L in front), turn it CW and lock it.
  4. Place the pneumatic discharge valve inside the center pipe, rotate it CCW until it drops down into place and lock.
  5. Insert the stabilising frame. Make sure it is locked into its place.
  6. Insert the float valve while rotating it.
  7. Connect the float valve to the stabilising frame. Make sure you hear the click when it is locked.
  8. Connect the water supply hose.
  9. Install the plate frame.
  10. Turn on water supply. Turn screw CCW. Make sure it does not leak.
  11. Connect the 2x air hoses to the actuation plate. Make sure hoses are not bent and its path is clear.
  12. Install the actuation plate to the frame
  13. Test each button.

thumbUP_gifanim Tip: In order to keep the shiny chrome coating of the actuation plate and buttons for years to come, DON’T use any toilet cleaner or any other aggressive cleaning material. Use only a soft paper towel with some window cleaner that contains Alcohol to clean and disinfect it.

thumbUP_gifanim Tip: Clean the cistern periodically.
Once a year or every several years depends on the water hardness level in your area.
In many places the water is hard and scale will build up on the cistern parts which eventually will cause it to malfunction.

thumbUP_gifanim Tip: A common fault is water overflow. The water supply does not stop when the cistern is full. The cistern is still functioning but the water supply keeps flowing into it. Because of an overflow safety design, the excess water flows to the toilet. The reason for this fault is that the clogged float can not move freely and the valve that controls the water supply will not cut off.

To solve and fix this fault, disassemble the parts as described above. Soak the parts for several hours in a water with citric salt solution. Use also a soft brush to remove any stubborn hard scale. Brush all parts and make sure that the gasket seal and its area (see part 11. above) is sooth and scale free. Pay close attention to the membrane (see part 8.1 d above) and make sure it is not damaged and that it is assembled correctly. This small gasket is responsible for cutting off the water supply when the float goes up.

When done, rinse all parts and reassemble it.

Voilà, you have completed the repair / fix / maintenance of your Grohe cistern.

Enjoy, Avi Schneor clapup_gifanim
* For Hebrew intro, follow to this link

Comments, remarks and updates are welcome.
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  1. Ji.

    Shalom Avi,
    Your guide is excellent. I have a question – my apartment has 4 Grohe in-wall cistern toilets that were installed about 18 years ago. The two toilets that get the most use are showing black rings inside the bowl just at the water line. I can clean the rings pretty easily with a toilet brush, but the are coming back more and more quickly. I am concerned that there may be a rubber O-ring or something inside the flush mechanism that is deteriorating and sending the black color into the bowl. Have you seen anything like that before? Any advice on what I should do to fix it?
    Thank you very much!

    • Avi Schneor

      Hello Jim and thanks for your message.
      In the model that my guide shows there is no black “O-ring”, so I have no idea where does it come from.
      Perhaps in your cisterns there is one. You’ll need to disassemble it to find out 🙂
      Another possibility relates to the water quality and to the build up of lime. Try to clean it with a lime remover or a citric salt solution.
      Good luck

  2. Bas

    Dear Avi,
    Thank you for a very nice guide! I followed the guide in order to stop water running from the cistern to the toilet. After assembling it the toilet won’t flush; I can see the valves are moving when blowing air in the hoses and also when pushing the buttons. But never the less it doesn’t flush. What have I fone wrong?!

    • Avi Schneor

      hello, it is impossible to help you in remote, I’m sorry.
      All I can suggest is to disassemble it again and reassemble it back, perhaps you missed something.
      Clean the parts with citric-salt, perhaps it is stuck somewhere
      Good luck

      • David

        Great guide – thank you and more informative that the plumber we had telling me we had to cut the wall out!

        When I reassembled, the toilet would not flush – I had the blue cap with the 6L mark, the wrong way round, so the piston was missing the lip to flush.

        All fixed and working.
        Thank you!

        • Avi Schneor

          Great news David
          I’m glad you managed to fix it by yourself
          have fun

  3. Kevin Walker

    I found your aid in dismantling the Grohe flush valve invaluable. Although my flush valve was a different model, the theory of your guide was invaluable. I had difficulty in seating the flush valve in the bottom of the tank but after covering the rubber washer with washing up liquid it easily clicked into place. Thanks

    • Avi Schneor

      Thank you Kevin.
      I appreciate your comment and I’m happy my guide helped you fix your Grohe system

  4. A B

    thank you very much Avi – really good “one stop shop” explanation!
    תודה רבה

    • Avi Schneor

      תודה רבה, מקווה שעזר לך לתקן ו/או לנקות את המיכל ושהכל פועל כשורה.


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electric hazard sign


1. Grohe system is attached to your house water supply.

Any procedure made to your Grohe flush system may cause damage to your equipment and can cause damage to your house. 
Any unauthorized handling of your Grohe flush system will void manufacturer warranty.
None of the following is recommended by me nor by the manufacturer, Grohe. 
These pages show only my personal experience and know-how.
If you follow any of the steps, you do it on your own risk and responsibility.

2. Copyright © 2011 Avi. All rights reserved. 

Content including all text and images in part or in whole may not be reproduced, retransmitted, stored, distributed, disseminated, sold, published, broadcast or circulated in any medium
without written consent of the author

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