Dual Flush Problems

Dual-flush toilets use separate reduced and full-flush settings to save water, but the buttons, cables, towers and seals must work together accurately. When one part sticks or wears, the toilet may run continuously, flush weakly or deliver the same volume from both buttons.

Before you worry

The smaller button is intended for liquid waste and the larger setting for a full flush. A noticeable difference between the two is normal. A fault exists when a button sticks, neither setting clears properly, or water continues entering the pan.

How to recognise the problem

• One button does not return after use.
• Both buttons produce the same flush.
• The reduced flush is too weak for normal use.
• The toilet runs after either button is pressed.
• The button assembly feels loose or disconnected.

Common causes

• Incorrect cable or rod adjustment.
• Worn flush-valve seal.
• Scale causing the flush tower to stick.
• Broken button springs or plastic clips.
• Water level set too low for the intended flush volume.

What you can safely check yourself

• Press each button separately and observe the response.
• Check whether the cistern fills to its normal level.
• Look for water trickling into the pan after the flush.
• Take a photo of the mechanism before adjustment.
• Turn off the isolation valve if the toilet will not stop running.

What you should never do

• Do not force a stuck button.
• Do not add weights to the mechanism.
• Do not raise the water level above the overflow.
• Do not fit incompatible generic parts without checking dimensions.

When to call a plumber

Call a plumber when the mechanism is concealed, parts are broken, water runs continuously, or adjustments do not restore a clear difference between the two flush settings.

How professionals solve it

A plumber inspects button travel, linkage, water level, valve seal and overflow. The mechanism is cleaned, adjusted or replaced with compatible parts, then both flush volumes are tested repeatedly to confirm proper operation and shut-off.

How to prevent it happening again

• Use each button gently and fully.
• Keep hard-water scale under control.
• Avoid cistern cleaning products that damage seals.
• Repair intermittent sticking before parts break.
• Use compatible replacement components.

Frequently asked questions