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Plumbing · November 20, 2025

Toilet Keeps Running? Here's What's Wrong and How to Fix It

A toilet that won't stop running is more than an annoyance — it can waste up to 200 gallons of water a day, quietly padding your bill. Most causes are simple and inexpensive to fix.

The flapper is the usual culprit

The flapper is the rubber seal at the bottom of the tank. Over time it warps or degrades and stops sealing, letting water leak continuously into the bowl. Replacing a flapper is a cheap, easy fix.

Check the float

If the float is set too high, water rises above the overflow tube and runs constantly. Adjusting the float arm or the fill valve so the water stops about an inch below the overflow tube usually solves it.

Inspect the fill valve

A worn fill valve may not shut off completely. If adjusting the float doesn't help, the fill valve assembly may need replacement.

The chain and handle

A chain that's too short holds the flapper slightly open; too long and it gets caught underneath. Adjust for a little slack when the flapper is closed.

When to call a plumber

If you've replaced the flapper and adjusted the float but the toilet still runs — or if you have multiple problem toilets — there may be a deeper issue with water pressure or the fill mechanism worth a professional look.

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