Quick Answer:
If the toilet takes much longer than it used to to stop refilling, start by checking the water supply and the fill valve. A restricted inlet screen, a partially closed stop valve, or a weak/clogged fill valve are common causes. With the tank lid off, watch the fill flow and follow the steps below to isolate and fix the problem. If cleaning the inlet screen or replacing the fill valve doesn’t help, call a plumber.
Why This Happens
Common reasons a toilet refills slowly include:
- Debris or mineral buildup in the inlet screen or supply line that reduces flow.
- A partially closed or failing shut-off (stop) valve that limits incoming water.
- A fill valve that is worn, clogged, or failing and no longer allows full flow into the tank.
- Low household water pressure or an issue with the municipal supply.
- Float or refill tube problems that change how the valve reacts during refill.
Step-by-Step What to Do
1. Observe and time a refill
Remove the tank lid, flush, and time how long the tank takes to refill and stop. Note whether the stream filling the tank is a steady strong flow or a weak trickle. This gives a baseline for later tests.
2. Confirm the shut-off valve is fully open
Locate the shut-off (angle) valve near the toilet and make sure it is turned fully counterclockwise to the open position. A partially closed valve is an easy fix and a common cause of slow refill.
3. Check fill rate at the valve
With the tank lid off, flush again and watch the flow from the fill valve into the tank. If the flow is slow even though the stop valve is open, the fill valve may be clogged or failing. Note whether water reaches the overflow tube and whether the fill tube directs water properly into the overflow.
4. Inspect the inlet screen and supply line
To inspect the screen safely:
- Turn the shut-off valve fully off.
- Place a small bucket or towel under the supply connection.
- Carefully disconnect the flexible supply line from the toilet (some lines are metal braided, some are plastic). Most supply fittings can be loosened with an adjustable wrench.
- Look for a small mesh screen or washer at the end of the supply or inside the valve inlet. Gently clean mineral deposits or debris with a brush and water.
- Reattach the supply, open the shut-off slowly, and test the refill.
5. Clean or replace the fill valve
If the inlet screen was clear but flow at the fill valve is still weak, the fill valve may be clogged internally or worn out. Some fill valves allow you to rinse or flush them following the manufacturer’s simple steps; others are inexpensive to replace. If you’re comfortable, replace the valve following the product instructions. If not, call a plumber.
6. Check the float and refill tube position
Ensure the float isn’t stuck and is set so the valve shuts off at the correct level. Confirm the refill tube feeds into the overflow tube, not below water level, and that it’s not obstructed.
7. Test other fixtures for low pressure
Run a sink or another fixture while observing toilet refill. If multiple fixtures have reduced flow, the problem might be low household pressure or a supply-side issue that needs attention from your water utility or a plumber.
8. Final test
After cleaning or replacing parts and confirming the shut-off is open, flush several times to confirm the refill returns to normal speed and stops reliably.
What Not to Do
- Don’t ignore a refill that’s getting slower—clogging and sediment buildup can worsen and lead to larger problems.
- Don’t force fittings or overtighten connections; that can damage threads and create leaks.
- Don’t use harsh chemicals in the tank to try to clear mineral buildup; they can damage parts and won’t reach the inlet screen.
- Don’t delay calling a professional if cleaning the inlet screen or replacing the fill valve doesn’t fix the problem—calling a plumber is appropriate in that case.
When to Call a Professional
Call a plumber if:
- Cleaning the inlet screen or replacing the fill valve doesn’t restore normal refill speed.
- You find corrosion, damaged threads, or a failing stop valve that needs replacement.
- Multiple fixtures have low pressure, suggesting a supply or pressure issue beyond the toilet.
- The slow refill began right after work on your house water supply—see Toilet runs after replacing main shutoff for related issues.
- The toilet also won’t stop running after a flush—see Toilet keeps running after flush if that is part of the problem.
Safety Notes
- Turn the shut-off valve fully off before disconnecting the supply line to avoid water spraying.
- Use a bucket and towels to catch residual water when disconnecting lines.
- Wear gloves and eye protection when working around debris and mineral deposits.
- If you smell sewage or see sewage backup, stop and call a plumber immediately—do not attempt extensive repairs.
Common Homeowner Questions
- How long should a toilet take to refill? A typical refill takes about 1–2 minutes; significantly longer means reduced flow or a malfunctioning valve.
- Can I just replace the fill valve myself? Yes, many fill valves are designed for homeowner replacement, but shut off the water and follow the manufacturer instructions; call a plumber if unsure.
- Could low water pressure in my house cause this? Yes—if multiple fixtures show reduced flow, it’s likely a pressure or supply issue rather than the toilet alone.
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