Fluidzon / Troubleshooting
Schwab Cistern Running Non-Stop — How to Fix
Water is leaking or continually flowing into the toilet bowl without flushing
Identify the model first.
The same symptom can have different causes. Confirm the cistern label, installation generation and applicable manufacturer instructions. Use only safely accessible checks; ask technical support when unsure.
Help identify my cistern →Check 01
Check the Flush Plate & Push Rod First
According to Schwab's official troubleshooting documentation for models 187, 198 and 199, the first thing to check is the flush plate push rod. If the push rod is not assembled correctly and protrudes too much, it permanently presses one of the flush buttons — causing the cistern to flush continuously. Solution: Check and correct the push rod adjustment. On model 198, push the rod to the very end before turning it 90 degrees to lock. On model 187, make sure you do not mix the front and top push rod adjustments — they are different lengths. Important: on model 198 with High Design flush plates, a side load on the buttons can cause the push rod to stick against the support plate, especially with thicker walls. Loosen the support plate, find the correct position to match the cover plate, and re-fix it.
Check 02
Inspect the Filling Valve
The filling valve is the second most common cause. Per the official Schwab fault tables, there are three filling valve faults that cause water to keep running: 1. Dirty or damaged rubber diaphragm — Open the cap at the back of the valve, take the diaphragm out and clean it under running water. If it is damaged or hardened, replace the fill valve assembly. 2. Water level set too high — The float is set above the overflow tube, so water continuously passes over the overflow into the bowl. Lower the valve float to the appropriate level (the MAX marking on the cistern wall). 3. Dirt in the valve filter — Sediment and calcium from UAE water reduces or blocks flow through the filter. Remove and clean the valve filter screen. This single step resolves roughly 40% of slow-fill and running complaints. On model 187, also check that the valve holder is fixed correctly to the cistern wall — if the filling valve is not in the correct position, it may not shut off properly.
Check 03
Inspect the Outlet Valve (Flush Valve)
The outlet valve is the most common cause of silent water leaking into the bowl. Schwab's official documentation lists five specific outlet valve faults: 1. Gasket is not clean or is damaged — Clean the gasket thoroughly. If it is worn, hardened, or has a nick in the sealing edge, replace it with Part 238 693. 2. Valve is not fixed properly to the cistern — On model 199, make correct back wall attachment of the valve bracket. On model 187, note the position of the lifting eye and lock the valve by rotating clockwise. On model 198, make correct attachment of the bridge. 3. Foreign object on the cistern floor — Debris sitting on the ground can prevent the valve from seating. Clean the cistern tank. 4. Damaged sealing edge on the valve seat — If the valve seat itself is scored or cracked, replace it with a new valve seat or the complete flush valve assembly (Part 239 070). 5. Valve seat not in correct position — Make sure the valve seat is pushed to the cistern tank bottom end. On model 187, a bigger hard particle can jam between the wall and the float, blocking valve function — remove the particle. On model 198, also check if the O-ring on the valve stem is missing — insert the O-ring if so.
Check 04
Check for Limescite Build-Up
Limestone and calcite deposits are listed as a standalone fault in all three model documents. UAE water is particularly hard, and mineral build-up on internal components can prevent the outlet valve from seating properly or the fill valve from closing. Clean all internal components thoroughly. If components are heavily fossilised (encrusted with mineral deposits), they may need to be replaced entirely as cleaning alone will not restore the original surface finish needed for a watertight seal.
Check 05
Rule Out the Toilet Pan
All three Schwab documents note this important diagnostic: some models of ceramic toilet pan leak water for 10–15 minutes or even longer after the flush. This is not a cistern fault. To test: fill the cistern to maximum, close the angle stop valve, then flush the water by removing the outlet valve. If water is still leaking into the bowl after the cistern is empty, the reason is the toilet pan itself, not the cistern. This test definitively rules out a cistern fault and prevents unnecessary parts replacement.
Check 06
Model 198: Check the Angle Stop Valve
Unique to model 198, Schwab's documentation lists a partially or minimally opened angle stop valve as a cause of continuous running. When the angle valve is not fully open, reduced water pressure can cause the fill valve to behave erratically — cycling on and off or failing to close completely. Open the angle stop valve to the maximum rate of flow. This is a free fix that takes seconds and is often overlooked.
These checks provide context for a support enquiry. Confirm any replacement article against the exact model drawing and manufacturer instructions.
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