Toilet Tank Not Filling
If a toilet tank fills slowly or not at all, the cause is usually a partly closed shutoff valve, a clogged or worn fill valve, or a float set too low. Most of these are 15-minute DIY fixes with a $10 to $30 part. A plumber typically charges $100 to $250 to replace a fill valve.
Typical pro cost
$100 to $300
- Urgency
- Fix this week
- DIY difficulty
- Easy
- Time to fix
- 15 to 45 minutes
- Prices
- US typical range
Last reviewed October 2026
Signs it's this problem
- The tank takes several minutes to refill or never fills
- Water trickles in with a hiss but the level stays low
- The bowl refills but the tank does not
- Weak flushes because the tank is half full
- No water enters the tank at all after a flush
Common causes
Shutoff valve partly closed
The oval handle behind the toilet may have been turned or the old valve is clogged with mineral scale.
Clogged fill valve
Sediment and scale build up in the fill valve cap and slow the water to a trickle.
Worn fill valve
Fill valves wear out after about 5 to 10 years and stop opening fully.
Float set too low
If the float or cup is adjusted too low, the valve shuts off before the tank is full.
Low house water pressure
If every fixture is weak, the problem is the home supply, not the toilet.
How to fix it, step by step
- 1
Check the shutoff valve behind the toilet: turn it fully counterclockwise (open).
- 2
Remove the tank lid and flush. Watch whether water enters through the fill valve, the tall tower on the left.
- 3
Raise the float or cup: turn the adjustment screw or slide the clip up so the water line sits about 1 inch below the top of the overflow tube.
- 4
Turn off the water, lift off the fill valve cap (most twist off), hold a cup over the valve and turn the water on briefly to flush out debris.
- 5
If it still fills slowly, replace the fill valve. Universal fill valves cost about $10 to $30 and install with no special tools.
- 6
If the shutoff valve itself is clogged or will not turn, have a plumber replace it.
Tools and materials
- Universal fill valve kit
- Adjustable wrench
- Sponge and towel
- Small cup or bucket
Approximate DIY cost: $10 to $30
Call a pro when
- The shutoff valve leaks or will not turn
- Every fixture in the house has low pressure
- Water leaks onto the floor around the tank
Toilet Tank Not Filling cost
| Job | Typical cost |
|---|---|
| Plumber: replace fill valve | $100–$250 |
| Replace toilet shutoff valve | $100–$200 |
| Rebuild tank (all internal parts) | $150–$300 |
| Fill valve part only (DIY) | $10–$30 |
Ranges are typical US prices compiled by FixHomeCost. Prices vary by region, home and contractor, so compare 2–3 local quotes.
Common questions
How long should a toilet tank take to fill?
About 30 to 60 seconds with normal water pressure. Several minutes points to a clogged fill valve or a partly closed shutoff valve.
Can I replace a fill valve myself?
Yes. Most homeowners can do it in 20 to 30 minutes with a universal kit and an adjustable wrench. Turn off the water and empty the tank first.
Why does my toilet tank fill but the bowl does not?
The refill tube may have slipped off the overflow tube, or the rim jets under the bowl edge are clogged with mineral scale.
Is a slow-filling toilet wasting water?
Not usually. A toilet that keeps running or refills on its own does. See our guide to a toilet that keeps running.
Related guides
This is general information, not a professional inspection. See how we research costs.