After a flush, the toilet tank should refill within about a minute so the toilet is ready for the next use. As the tank refills, a small refill tube also sends water into the bowl to restore the normal bowl water level. With a tank that isn’t working right because it refills slowly, the toilet may take several minutes to recover between flushes.
In most cases, slow refilling is caused by restricted water supply flow or a worn or constricted fill valve inside the tank rather than a serious plumbing problem. Mineral deposits, debris in the supply line, or a partially closed shutoff valve can reduce the flow of water entering the tank.
Start by confirming the symptoms below, then follow the steps to restore normal refill speed.
Quick Answer
A toilet that fills slowly is typically the result of debris blocking the fill valve or restricted water flow through the supply line. Making sure the water supply valve is turned all of the way on or cleaning or replacing the fill valve usually restores normal refill speed.
Common Signs of a Slow-Filling Toilet
- Tank takes several minutes to refill
- Weak or reduced water flow into the tank
- Hissing sound lasts longer than normal
- Toilet cannot be flushed again quickly
- Water trickles instead of flowing steadily
Likely Causes
Slow tank refill commonly results from:
- Mineral or sediment buildup in the fill valve
- Partially closed shutoff valve
- Kinked or restricted supply line
- Aging or worn fill valve
- Low household water pressure
- Debris entering plumbing after water service work
Tools & Materials
You may need:
- Adjustable wrench
- Small cup or sponge
- Towel or bucket
- Replacement fill valve
- Rubber gloves
Have towels ready before disconnecting any water connections.
Step-by-Step: How to Fix a Toilet That Fills Slowly
1. Check the Shutoff Valve
Locate the water shutoff valve beneath the toilet. Turn it counterclockwise to confirm it is fully open. Even a partially closed valve can significantly reduce refill speed.
Flush the toilet and check whether this has solved the problem.
2. Inspect the Supply Line
Examine the flexible supply tube connecting the wall valve to the tank.
Look for:
- Sharp bends or kinks that could restrict flow
- Mineral buildup at connections
- Signs of internal restriction
Straighten or replace the supply line if the flow of water looks like it could be restricted.
3. Clean Debris from the Fill Valve
Mineral particles or debris from the water supply can sometimes clog the fill valve and slow the refill rate. Flushing the valve may restore normal water flow. Here’s how to do this:
- Turn off the water supply (clockwise). Close the shutoff valve located on the wall behind the toilet.
- Remove the tank lid.
- Locate the fill valve—the tall mechanism inside the tank connected to the water supply line.
- Remove the valve cap. On most modern fill valves, the cap at the top twists slightly and lifts off. Hold the valve body with one hand and rotate the top cap about 1/8 turn counterclockwise, then lift it off.
- Flush the valve. Place a cup upside down over the valve opening so it doesn’t squirt all over the place.
- Turn the water supply on for about 10 to 15 seconds to flush debris from the valve.
- Turn the water off again and reassemble the valve.
- Turn the water supply back on and test the refill speed.
If the toilet still fills slowly after cleaning the valve, the fill valve may be worn—you should replace it.
See: How to Replace a Toilet Fill Valve.
Reassemble and test the refill speed again.
4. Check Float Adjustment
If the float sits too low, the valve may restrict incoming water.
Adjust the float slightly upward and test again. The final water level should stop about 1/2 inch below the top of the overflow tube.
When the Problem May Be More Serious
Slow refill may indicate:
- Low water pressure affecting multiple fixtures
- Blocked household supply piping
- Failing shutoff valve inside the wall
For these issues or if sinks or showers also show reduced pressure, it’s time to hire a plumber.
Preventing Future Slow Refill Problems
- Periodically operate shutoff valves to prevent sticking
- Replace aging supply lines
- Flush plumbing after municipal water work
- Replace fill valves showing early wear
To Hire a Plumber…
If the repair turns out to be more complicated than expected, you can always find a qualified plumber near you.
For hiring advice, see Trade Secrets for Hiring the Right Plumber.
Related Articles
If you’re not sure what’s causing the problem, see our
Toilet Repair and Troubleshooting Guide for a complete diagnostic overview.
Also see:
