If your toilet won’t stop running after flushing, the culprit is often the fill valve. The fill valve controls water entering the tank, shutting off when the tank is full. But when it fails, water continuously flows into the tank and down the overflow tube—wasting gallons of water and driving up your utility bill. In this guide, we’ll explain the most common reasons why a fill valve keeps running, how to fix it, and the best replacement valves to restore quiet, efficient toilet operation.
Why Does a Fill Valve Keep Running?
There are several possible causes of a continuously running fill valve:
- Float set too high: Water level rises above the overflow tube, keeping the valve open.
- Worn-out fill valve: Internal seals fail, allowing water to leak through.
- Debris or mineral buildup: Sediment blocks the valve from closing completely.
- Misaligned float arm: A bent or stuck float keeps the valve open.
- Old or damaged valve: Valves typically wear out after 5–7 years of use.
How to Fix a Running Fill Valve
Try these troubleshooting steps before replacing the valve:
- Check the water level: Adjust the screw on top of the fill valve or move the float clip to lower the water line.
- Inspect the float: Make sure it moves freely and isn’t rubbing against the tank wall.
- Flush debris: Turn off the water, remove the top of the fill valve, and rinse it out under running water.
- Test again: Turn the water back on, flush, and see if the problem is resolved.
If these steps don’t work, it’s time to replace the valve.
Best Replacement Fill Valves
Here are some of the most reliable replacement fill valves available today:
Fluidmaster 400A Universal Fill Valve
Best Overall
- Adjustable height: 8″–14″
- Fits most 2-piece and 1-piece toilets
- DIY installation in under 30 minutes
Pros: Affordable, widely compatible, long-lasting
Cons: Louder than premium quiet-fill models
Korky 528MP QuietFill Platinum Valve
Best Quiet Option
- Height adjustable: 7.75″–13.5″
- Designed for noise-free operation
- Premium construction for durability
Pros: Very quiet, durable, efficient
Cons: Slightly higher cost
Kohler GP1083167 Silent Fill Valve Kit
Best OEM Replacement
- Designed specifically for Kohler toilets, including Class Five models
- Silent-fill technology reduces refill noise
- Adjustable for different tank sizes
Pros: Perfect fit, quiet, OEM reliability
Cons: Costs more than universal models
Comparison Table
| Product | Best For | Adjustable Height | Noise Level | Price Link |
|---|---|---|---|---|
| Fluidmaster 400A | Universal replacement | 8″–14″ | Moderate | View Price |
| Korky 528MP | Quiet performance | 7.75″–13.5″ | Very quiet | View Price |
| Kohler GP1083167 | OEM replacement | 7.75″–13.5″ | Silent-fill, very quiet | View Price |
FAQ
Why won’t my fill valve stop running?
Most often, the float is set too high or the valve is worn out. Cleaning and adjusting may help, but replacement is usually the best fix.
Can I adjust the fill valve myself?
Yes. Most fill valves have an adjustment screw or clip that raises or lowers the float height.
How much water does a running fill valve waste?
A running toilet can waste hundreds of gallons per day, significantly increasing your water bill.
How long do fill valves last?
Typically 5–7 years. Hard water may shorten lifespan.
Can I replace a fill valve without a plumber?
Yes. Most replacement kits are DIY-friendly and require only basic tools.
Conclusion & Call-to-Action
If your fill valve keeps running, you don’t have to live with wasted water and high bills. Adjustments and cleaning may help temporarily, but replacement is the best long-term solution. The Fluidmaster 400A is an affordable universal fix, the Korky 528MP provides whisper-quiet operation, and the Kohler GP1083167 is perfect for Kohler toilets.
Order your replacement fill valve today and enjoy a quiet, efficient, leak-free toilet.