The free float-arm tweak that stops phantom flushing and overflow

You will need

• Flathead screwdriver · Already in your kitchen drawer — free
• Adjustable pliers (optional) · Bunnings, ~$12 if you don't own a pair
• Cloth or small towel · Woolies, ~$2 — to wipe up any drips
• Marker pen · Any brand, from home — to mark your starting water level

Step 1

Mark your current water level

Take the lid off your cistern and set it safely aside on the floor. Use a marker to draw a line on the inside wall where the water currently sits. This gives you a reference point so you can see exactly how much you're adjusting.

Step 2

Identify your fill valve type

Look inside — you'll see either an old-style ball float (a plastic ball on a long arm) or a modern tower-style fill valve with a float collar that slides up and down the shaft. Both are adjustable, just in slightly different ways. Don't touch anything yet, just look.

Step 3

Adjust a ball float arm

If you have the ball-on-arm style, gently bend the metal or plastic arm slightly downward to lower the water level, or upward to raise it. You only need a small movement — about 1 cm of bend changes the level noticeably. Do the adjustment, flush, and let it refill to check the new level.

Step 4

Adjust a tower-style fill valve

Find the adjustment screw or pinch clip on the side of the tower unit — it's usually near the top and marked with + and − arrows. Turn the screw clockwise to raise the water level or anti-clockwise to lower it, or slide the float collar up or down the shaft and lock it. Flush and refill to check — the water should sit about 2–3 cm below the overflow tube inside the cistern.

Step 5

Check the overflow tube height

The overflow tube is the open pipe standing up in the middle of the cistern — water should never be reaching its top. If your adjusted level still sits above that tube, lower the float further. Water trickling into the bowl constantly is usually just the level being too high.

Step 6

Replace the lid and do a final flush test

Put the cistern lid back on and flush two or three times, watching and listening for a clean fill and a quiet stop. No hissing, no running water sound after 60 seconds means you've nailed it. Job done.

The stop point

If the fill valve is cracked, visibly corroded, or won't stop running even after adjustment → stop, turn off the water supply valve at the wall behind the toilet, and call a licensed plumber. A replacement fill valve is a $20 part but requires a plumber to fit legally in most Australian states.

If that is where you are: public cost guides put a toilet repair / replacement job at $150 to $450 (sources: ServiceSeeking 2026 price guides; Airtasker cost guides (2024, handyman tier); captured 2026-07-12). See the full cost guide.

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