FAQ
TL;DR: 6 mm fitting clearance can choke flow; "the water does not flow, it just drips." To fix a slow‑filling Geberit, clean the inlet filter, test supply by removing the hose, and straighten any kinked lines. [Elektroda, ppwielki, post #20460744]
Why it matters: For homeowners and installers with concealed frames and limited access, this FAQ speeds diagnosis and fixes slow fills and post‑flush drips.
Quick Facts
- PEX/AluPEX fittings can narrow a 16 mm line to ~6 mm, severely limiting cistern fill rate. [Elektroda, ppwielki, post #20460744]
- There’s an inlet filter at the cistern connection; remove the hose and verify free flow from the hose itself. [Elektroda, Zbych034, post #20460705]
- Service access is through the flush button opening; remove the plate, shut off water, and pull the fill valve for cleaning. [Elektroda, Parowy, post #17657278]
- Geberit float valves use a tiny pinhole under a red rubber band; limescale here causes trickle or no fill. [Elektroda, Dorianix, post #21367140]
- New frames may retain transport locks/foam; removing these restores normal filling and shutoff. [Elektroda, sq3evp, post #20460903]
How do I fix a Geberit concealed cistern that fills slowly?
Start at the service opening. Remove the flush plate, close the cistern shut‑off, then pull the fill valve out. Disassemble and clean the valve and screens, then reassemble and test.
- Remove the button/plate.
- Close supply and extract the fill valve.
- Rinse debris, reassemble, and set float height. [Elektroda, Parowy, post #17657278]
How do I check the inlet filter and water supply to the cistern?
Unscrew the flexible hose at the cistern inlet valve. Inspect and clean the small inlet filter at that connection. Open the shut‑off and observe flow from the hose only. Strong hose flow means a valve issue; weak flow points upstream. [Elektroda, Zbych034, post #20460705]
Is the fill valve or my water pressure to blame?
Compare pressure at other taps or showers. If they run strong, focus on the cistern valve. "The filling valve is to blame." If other fixtures are also weak, investigate the supply line. [Elektroda, Parowy, post #17657278]
My brand-new Geberit fills slowly and leaks a bit—what should I check?
Look for a transport lock or packing foam left in the actuator chamber. One installer fixed the issue by removing a styrofoam piece. Request the removal page from your distributor if necessary. After removal, filling and shutoff normalized. [Elektroda, sq3evp, post #20460903]
Why does water keep trickling into the bowl after flushing?
Scale on the main seal seat can prevent complete closure, causing a slow drip. Soak the seat with vinegar, then scrub using a long, flexible brush. Clean and lightly lubricate rubber components with a waterproof agent. This restores sealing and stops the trickle. [Elektroda, Dorianix, post #21367140]
How do I clean the tiny pinhole in the Geberit float valve?
Remove the movable arm and find the red rubber band inside. Under it is a pinhole that controls flow and shutoff. Use a torch and magnifier to spot scale, then clear the pinhole. "A vacuum is created and the water does not continue to flow." One user needed four disassemblies to see it. [Elektroda, Dorianix, post #21367140]
Can a twisted or bent hose slow down cistern filling?
Yes. A kinked or twisted hose restricts flow and mimics valve failure. Inspect the hose routing and straighten or replace if needed. This quick check can restore normal refill speed. [Elektroda, ppwielki, post #20460246]
Does PEX/AluPEX piping affect cistern fill speed?
Yes. Multiple elbows or tees add friction and reduce flow to the cistern. Even with 16 mm pipe, some fittings have only 6 mm clearance. That restriction can limit fill to a slow trickle. Confirm by testing flow at the hose. [Elektroda, ppwielki, post #20460744]
What access do I have on a concealed frame to service the valve?
Use the flush button opening as the service port. Remove the plate to reach the shut‑off and the fill valve body. Pull the valve through this opening for cleaning or replacement. Frames are designed for service from here. [Elektroda, Parowy, post #17657278]
What tools or supplies help with this repair?
A flashlight and magnifying glass help locate the tiny pinhole and scale. Vinegar softens limescale; use a long, flexible brush to scrub. After cleaning, apply a thin film of waterproof lubricant on rubber seals. Reassemble and test shutoff performance. [Elektroda, Dorianix, post #21367140]
Where can I see how the mechanism works before I open it?
Watch a short animation or video guide of the Geberit mechanism. Search YouTube for your model’s float valve. Seeing the sequence improves understanding and confidence before disassembly. Visuals clarify filling and shutoff timing. [Elektroda, Parowy, post #17657314]
How often should I re-check filters on a new installation?
Right after commissioning, debris can repeatedly clog small filters. Re-check and clean the inlet filter and valve screens soon after first use. If flow stays weak, test at the hose to isolate upstream restrictions. Repeat until the line runs clear. [Elektroda, ppwielki, post #20460744]
only the siphon is a problem. Is there a schematic of how to fix it?
