Repair, fix and maintain Grohe flush system

by Updated: Nov 11, 2020diy-miscellaneous42 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 a. above.

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 in 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.

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. Ed Frank

    hi, I have a Grohe concealed cistern and to empty the cistern requires 3 pushes. Can i repair the pneumatic valve or must it be replaced?

    • Avi Schneor

      hello Ed
      You probably need to replace the pneumatic button/s but this needs some more tests to confirm.
      Bellows piston are very hard to repair and Grohe does not sell parts of the actuation plate.
      Good luck

  2. נחום

    אבי הסברים מעולים
    האם ניתן לקבל הגדרה של האטם הטבעתי של הסיפון או היכן אתה חושב ניתן לרכוש שכזה

    • Avi Schneor

      תודה נחום
      המקור הטוב ביותר לחלפים הוא היבואן הרשמי של גרוהה.
      אם תתעקש לחפש לבד וכוונתך לדגם הזה בדיוק ולאטם הסיליקון התחתון, חפש אטם מספר דגם 42-687
      בכל מקרה, לפני החלפה אני מציע לבצע ניקוי אבנית למיכל ולנקות היטב את התחתית. מספיקה אבן אחת קטנטונת לגרום לאי-אטימה.

  3. Brian M.C.

    Hi, great instruction and appreciate the detail. I followed it and took the parts out for a good clean. The system is still very slow to fill.

    Would you advise that I go through the decal process or could there be a part restricting the flow?

    Appreciate your help,


    • Avi Schneor

      Thank you.
      Water supply is regulated by a valve (section 2. and 6. in my post). Try to open it more and if this does not help, disassemble the connection (shut off the house supply or a safety valve that controls this line), clean the connection and the small hose and check if flow to this point is normal.
      Good luck


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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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