When you flush your toilet, the fill valve should immediately let water flow into the tank, preparing it for the next flush. But if the fill valve is not filling after flushing, you’re left with a toilet that won’t work properly. This is a common problem with simple causes — and usually simple solutions. In this guide, we’ll explain why your fill valve isn’t refilling the tank, how to fix it, and when to replace it with a reliable new valve.
How a Fill Valve Works
The fill valve sits inside your toilet cistern (tank). When you flush, water leaves the tank and the float attached to the valve drops. This drop should trigger the valve to open and let fresh water in. Once the water reaches the right level, the float rises and shuts the valve again. If the tank isn’t refilling, the process is being interrupted somewhere.
Common Causes of a Fill Valve Not Filling
- Water supply is shut off: The isolation valve behind the toilet may be turned off or partially closed.
- Clogged inlet: Sediment or limescale may block the valve’s inlet, stopping water from entering.
- Stuck float: If the float is caught or jammed, the valve won’t open after flushing.
- Debris in the valve seal: Dirt or grit inside the valve can prevent proper operation.
- Worn or broken fill valve: If the valve has aged or cracked, it may fail to open at all.
How to Fix a Fill Valve That Won’t Refill
- Check the water supply: Ensure the shutoff valve is fully open.
- Inspect the float: Make sure it moves freely up and down without sticking to the side of the tank.
- Clean the fill valve: Remove the top cap and flush out any dirt or sediment that may be blocking flow.
- Adjust the float level: If it’s set too high, the valve may not trigger correctly. Adjust it so the water stops about 1 inch below the overflow tube.
- Replace the seal: Many valves allow you to replace just the rubber seal inside instead of the entire valve.
- Replace the valve: If none of the above works, install a new fill valve for a permanent fix.
When to Replace the Fill Valve
Fill valves typically last 5–7 years, but hard water can shorten that lifespan. If your valve is old, cracked, or continues to fail after cleaning, replacement is the easiest and most reliable solution. Modern fill valves are inexpensive, easy to install, and designed to fit most toilets.
Recommended Replacement Fill Valves
Fluidmaster 400A Universal Fill Valve
- Industry standard replacement.
- Fits most toilets, adjustable height.
- Proven reliability and easy installation.
Verdict: Best universal replacement valve for most homeowners.
Korky QuietFILL 528MP Fill Valve
- Tool-free installation and adjustments.
- Quieter than most factory valves.
- Universal compatibility with leading toilet brands.
Verdict: The quietest and most beginner-friendly DIY option.
Fluidmaster 400CRP14 Complete Toilet Repair Kit
- Includes both fill valve and flapper.
- Great for older toilets needing multiple parts replaced.
- Affordable way to restore full toilet function.
Verdict: Best for a complete fix if your flapper is also leaking.
Comparison Table
| Model | Best For | Key Features | Price |
|---|---|---|---|
| Fluidmaster 400A | Universal replacement | Adjustable height, proven design | Check Price |
| Korky QuietFILL 528MP | Quiet operation | Tool-free install, noise reduction | Check Price |
| Fluidmaster 400CRP14 Kit | Complete repair | Fill valve + flapper included | Check Price |
FAQ
- Why won’t my toilet tank refill?
The most common reasons are a shut-off supply, clogged valve, stuck float, or worn valve seal. - Can I fix it without replacing the valve?
Yes, often cleaning the valve or replacing the seal will restore it. But if the valve is old or cracked, replacement is best. - Do I need special tools to replace a fill valve?
No, most require just an adjustable wrench and can be installed in under 30 minutes. - How do I know if I need a full repair kit?
If your toilet also leaks from the flapper, a repair kit with both parts is the smarter choice.
Conclusion & Call to Action
If your fill valve isn’t refilling after flushing, the issue could be as simple as a stuck float, debris buildup, or a shut-off water supply. Cleaning and adjusting can solve many cases, but if your valve is worn out, replacement is the fastest and most reliable fix.
Reliable, easy-to-install options like the Fluidmaster 400A or the Korky QuietFILL will have your toilet filling smoothly again in no time.