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A running toilet is one of the most common plumbing problems in Atlanta homes — and one of the most expensive to ignore. A toilet that runs continuously can waste 200 gallons of water per day. At Atlanta’s current water and sewer rates, that adds up to $15 to $30 per month in wasted utility costs, silently draining money while you sleep.
The fix is usually under $30 and takes less than an hour. Here’s how to figure out exactly what’s wrong.
Understanding How a Toilet Tank Works
When you flush, the tank empties into the bowl through the flapper (the rubber seal at the bottom of the tank). As the tank empties, the fill valve refills it. The float attached to the fill valve rises with the water level and shuts off the fill valve when the water reaches the correct height. The overflow tube prevents overfilling by directing excess water directly into the bowl if the water level gets too high.
A toilet runs continuously when water is leaking from the tank into the bowl faster than the fill valve can keep up — or when the fill valve itself doesn’t shut off properly. There are three main causes.
Cause 1: A Faulty Flapper
The flapper is the most common cause of a running toilet by a wide margin. It’s a rubber seal that sits over the drain opening at the bottom of the tank. Over time, rubber flappers deteriorate — they warp, crack, or develop mineral deposits that prevent a complete seal. When the flapper doesn’t seal properly, water leaks continuously from the tank into the bowl, triggering the fill valve to run constantly to keep up.
The dye test: Put a few drops of food coloring in the tank. Wait 15 minutes without flushing. If color appears in the bowl, the flapper is leaking.
The fix: A replacement flapper costs $5 to $10 at any hardware store. Turn off the water supply valve behind the toilet, flush to empty the tank, remove the old flapper (it hooks onto two pegs and unclips from the chain), install the new one, restore water supply, and test. This is the most beginner-friendly plumbing repair there is.
Cause 2: A Misadjusted or Failing Fill Valve
If the flapper checks out but the toilet still runs, the fill valve is the next suspect. Two things can go wrong:
- Float set too high: If the float is adjusted so the tank fills above the overflow tube, water constantly drains through the overflow tube into the bowl. You’ll hear a steady trickling sound. The fix: adjust the float down — on most modern fill valves, there’s an adjustment screw or clip on the valve itself. Set the water level about one inch below the top of the overflow tube.
- Fill valve failure: Fill valves wear out and can develop internal failures that cause them to run intermittently or continuously even when the float is set correctly. Replacement fill valves run $10 to $15 and the installation is straightforward.
Cause 3: The Overflow Tube Height
If the overflow tube is cut too short (below the water level the fill valve is set to maintain), water will continuously flow down the overflow tube regardless of flapper condition. This is less common but worth checking: the water level in the tank should sit at least one inch below the top of the overflow tube.
The Intermittent Runner
Some toilets don’t run continuously — they cycle on for 10 to 30 seconds every hour or so on their own. This is called a phantom flush, and it’s caused by a slow flapper leak. The tank gradually empties until the fill valve triggers, refills, and shuts off. The dye test above will identify this.
Replacing Both Components at Once
If your toilet is more than 10 to 15 years old, or if you’re already doing the repair, consider replacing both the flapper and fill valve together. Toilet repair kits including both components sell for $12 to $20 and take about 20 minutes to install. It’s better maintenance than replacing one part at a time.
When a Running Toilet Signals a Bigger Problem
Occasionally, a running toilet is caused by a cracked overflow tube, a damaged flush valve seat (the ring the flapper sits on), or a faulty fill valve that can’t be adjusted to hold. These require more involved repair or full tank rebuild kits. A plumber can typically diagnose and repair these in one service visit.
Fix and Flow handles toilet repairs, full tank rebuilds, and toilet replacement throughout Atlanta. If you’ve replaced the flapper and fill valve and the toilet is still running, give us a call at (404) 800-FLOW or visit our toilet repair page. We’ll get it sorted out.