Quick answer
A toilet tank that will not fill is most often a partly closed supply valve, a float set too low, or a fill valve clogged with grit. Open the valve behind the toilet fully, raise the float, and flush debris out of the fill valve. If the tank fills and then drains away, the flapper is leaking. A worn fill valve is replaced, not repaired. HomeAdvisor puts typical toilet repairs at $150–$391. Call (888) 217-6781 to reach a plumbing company taking calls in your ZIP.
Follow the short menu, then your 5-digit ZIP. The line goes quiet for a few seconds while it connects; stay on. If it does not connect, call once more: companies taking calls change minute to minute.
Written & reviewed by Marcus ReedIICRC WRT
Reviewed November 4, 2026· Next review May 2027
When a toilet tank stays empty, or takes minutes to refill, the water is either not getting in or getting out as fast as it arrives. Lift the tank lid and watch one flush: it tells you which.
Check These First
- 1The supply valve. The small valve on the wall behind the toilet should be fully open, counterclockwise. A valve that was bumped half-closed is the most common cause, and an old multi-turn valve can also seize partly shut inside.
- 2The float. On the fill valve, the float sets the water level. If it is set low, the tank stops filling early. Adjust it so the water stops about an inch below the top of the overflow tube.
- 3The fill valve. Shut off the water, remove the cap on the fill valve (most twist off a quarter turn), hold a cup over it and turn the water on briefly to flush out grit. Sediment after plumbing work or a city main repair is common.
- 4The refill tube. The small hose that clips onto the overflow tube should be attached; if it has fallen inside, the bowl does not refill properly.
Fills, Then Empties
If water comes in but the tank level drops again, the flapper at the bottom is not sealing. A warped flapper, a chain that is too short, or mineral buildup on the seat lets water run into the bowl. That also shows up as a toilet that refills by itself; see toilet running randomly.
Talk to a plumber about this
One call reaches a plumbing company taking calls in your ZIP.
What Usually Fails
| What you see | Likely cause |
|---|---|
| No water enters at all, valve open | Fill valve failed, or supply line kinked or blocked |
| Slow hissing fill | Grit in the fill valve, or the supply valve partly shut |
| Fills to a low level | Float set too low |
| Fills, then water runs into the bowl | Flapper or flush valve seal |
| Water on the floor while filling | Supply line or fill valve seal; see toilet leaking between tank and bowl |
What a Repair Costs
A fill valve is an inexpensive part and a short job. HomeAdvisor puts typical toilet repairs at $150–$391, and Fixr puts simple jobs at $60–$200. See toilet repair.
The Call
Call when the supply valve will not open or turn, when the supply line or valve is leaking, or when a new fill valve does not fix it. (888) 217-6781 connects you to a plumbing company taking calls in your ZIP. Follow the short menu, enter your 5-digit ZIP and stay on while it connects; if it does not connect, call once more, because the companies taking calls change minute to minute.
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Frequently Asked Questions
Why is my toilet tank not filling with water?
A partly closed supply valve, a float set too low, a fill valve clogged with sediment, or a cracked fill tube. If it fills and then empties, the flapper is leaking.
Why does my toilet tank fill so slowly?
Usually grit in the fill valve or its inlet, or low pressure from a supply valve that is not fully open. Flushing the fill valve often fixes it.
How much does it cost to fix a toilet that won't fill?
HomeAdvisor puts typical toilet repairs at $150–$391; Fixr puts simple jobs such as a fill valve at $60–$200.
Sources
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Disclaimer: HearthDry is an independent educational resource. This article is for informational purposes only and does not constitute professional, legal, or insurance advice. Consult licensed professionals before making decisions about your property or insurance claims.
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