How to Fix a Running Toilet Easily in 5 Simple Steps

Hearing your toilet run nonstop is annoying—and wasteful. A running toilet can waste hundreds of gallons of water, spike your water bill, and even damage your bathroom floor over time. The right toilet repair can save you money and hassle. In this guide, we’ll cover the most common causes and simple DIY fixes—no plumbing experience needed! For stubborn leaks, check out our guide on the best cleaning solutions for toilets.

Key Takeaways

• Adjust or replace the flapper if water leaks into the bowl.
• Check the fill valve for proper water shutoff.
• Shorten the overflow tube if water spills into it.
• Inspect the chain for tangles or improper slack.

1. Check the Flapper for Leaks

The flapper is the rubber seal at the tank’s base. If it’s worn or misaligned, water leaks into the bowl, causing constant refilling. Here’s how to fix it:

• Turn off the water supply (valve behind the toilet).
• Flush to drain the tank, then inspect the flapper for cracks or warping.
• Adjust the chain so it has 1/2-inch slack—too tight keeps it open, too loose prevents sealing.
• Replace the flapper if damaged (universal kits cost under $10).

Pro Tip: Add a few drops of food-safe dye to the tank. If color appears in the bowl without flushing, the flapper leaks.

2. Adjust the Fill Valve

A faulty fill valve (ballcock) fails to shut off water flow. To fix:

• Lift the float arm while the tank fills. If water stops, the valve works but needs adjustment.
• Bend the float arm downward to lower the water level (should sit 1 inch below the overflow tube).
• For newer models, twist the adjustment screw clockwise to lower the fill line.

If adjusting doesn’t help, replace the valve (15-minute job with a $20 kit).

3. Shorten the Overflow Tube

If water spills into the overflow tube, the tank overfills. Fix it by:

• Measuring the tube—it should be 1 inch shorter than the fill valve’s critical level mark.
• Cutting the tube with a hacksaw if too tall (rare, but happens in older toilets).

4. Inspect the Chain and Flush Lever

A tangled chain or stuck lever keeps the flapper open. Solutions:

• Ensure the chain has minimal slack—excess length can loop under the flapper.
• Lubricate the flush lever with petroleum jelly if stiff.

5. Test for Silent Leaks

Some leaks are silent. To detect:

• Place a dry paper towel around the toilet base—wet spots indicate external leaks.
• Listen for hissing near the supply line (tighten connections or replace the washer).

Summary Table: Common Running Toilet Fixes

Final Words

Fixing a running toilet is simpler than most think—often requiring just a flapper tweak or valve adjustment. Regular checks prevent costly water waste. For more home fixes, explore our guide on hardwood floor care. Need professional help? EPA’s WaterSense lists certified plumbers.