Toilet Keeps Running or Won't Flush? Here's Why (and How to Fix It)

A constantly running toilet wastes 150–200 litres of water per day, adding RM30–80 to your monthly Syabas bill. Most cistern problems come from just a few common faults that are quick and inexpensive to fix.

Problem 1: Float Valve Set Too High

The float tells the cistern when to stop filling. If the water level rises above the overflow pipe, water constantly trickles into the bowl. Fix: Adjust the float arm downward so water stops 2–3cm below the overflow outlet. On modern dual-flush cisterns, there's usually a screw adjustment on the valve body.

Problem 2: Worn Flush Valve (Flapper)

The rubber flapper at the bottom of the cistern seals the flush valve. KL's chlorinated water hardens rubber over time, preventing a watertight seal. Result: water continuously seeps into the bowl. A universal replacement flapper costs RM8–20 at any hardware shop and takes 5 minutes to install.

Problem 3: Cracked Overflow Tube

If the overflow tube is cracked or too short, water bypasses it and drains directly into the bowl. This requires replacement of the entire flush valve assembly — a job a plumber completes in under an hour.

Problem 4: Calcium Build-up

KL's moderately hard mains water causes calcium deposits that clog the fill valve, making the cistern fill very slowly with a hissing noise. Soak the valve in white vinegar or replace the fill valve (RM20–50 for a quality replacement).

Problem 5: Weak Flush

If pressing the flush button gives a weak or partial flush, check the water level first — it should be at the marked line. If the issue persists, the dual-flush cartridge may need replacement. These are brand-specific (Grohe, Toto, American Standard) and cost RM50–200.

When to Call a Plumber

If water leaks from the base of the toilet, the toilet rocks when you sit, or multiple flushes fail to clear the bowl — these indicate a more serious issue requiring professional attention. HandyManBuilts handles all toilet repairs across KL same-day.