Quick Answer:
If your toilet tank takes an unusually long time to refill, start by lifting the tank lid and watching the fill valve. A healthy refill is a steady, fairly strong stream into the overflow tube or into the fill cup. If the stream looks weak or sputtery, the inlet screen or the fill valve itself is often the cause.
Why This Happens
- Partially closed shutoff or a kinked supply line limits water flow into the tank.
- Mineral deposits or debris clog the inlet screen or the fill-valve mechanism, reducing flow.
- Worn or failing fill valves don’t open fully and slow refill.
- Low household water pressure or recent plumbing work can change flow behavior — see Slow refill after plumbing repair if this began after work, or Slow refill only at night if the issue appears at certain times.
Step-by-Step What to Do
1. Observe the refill
- Lift the tank lid and set it aside on a towel so it won’t fall or break.
- Flush and watch how water enters the tank. You should see a steady stream either into the overflow tube (for older systems) or into the fill cup/valve area (for modern fill valves).
2. Confirm the shutoff and supply
- Find the shutoff valve behind the toilet and confirm it is fully open by turning it counterclockwise until it stops.
- Check the supply hose for kinks and make sure the supply connection at the valve is tight but not over-tightened.
3. Inspect the inlet screen
- Turn off the water at the shutoff and flush to empty the tank.
- Disconnect the supply hose at the bottom of the tank or open the fill-valve cap (follow the manufacturer instructions for your valve type).
- Look for a small mesh screen or filter at the inlet. If it’s dirty, rinse it gently under running water or remove debris with a soft brush.
- Reassemble, turn the water back on, and test the refill.
4. Check and adjust the fill valve
- If the inlet screen was clean but flow is still weak, the fill valve may be partially blocked or worn. Some valves have an adjustable height or cleaning cap—refer to the valve label for instructions.
- If adjustment or cleaning doesn’t restore normal flow, replacing the fill valve is a common, inexpensive fix, but only attempt replacements if you’re comfortable with basic plumbing tasks.
5. Test for household pressure issues
- Check other taps in the house. If multiple fixtures have low flow, the problem may be household water pressure — contact your water supplier or a plumber.
What Not to Do
- Don’t assume slow refill is normal aging—restricted flow wastes time and water.
- Don’t ignore ongoing leaks or persistent low flow; if you can’t identify the cause, a plumber is appropriate.
- Don’t force or overtighten plastic fittings; that can crack parts and cause leaks.
- Don’t use sharp metal tools to scrape screens or internal rubber parts—use soft brushes or cloths to avoid damage.
When to Call a Professional
- If you can’t find the cause after the basic checks above.
- If the supply line leaks when you open or close the shutoff, or if fittings are corroded.
- If multiple fixtures in the home have low pressure or if water pressure changes suddenly.
- If you’re uncomfortable with replacing the fill valve or disconnecting supply lines.
Safety Notes
- Always turn off the shutoff valve before disconnecting the supply line or working on the fill valve.
- Place the tank lid on a towel or flat surface to prevent chipping or shattering.
- Wear gloves and eye protection if you’re dealing with mineral buildup or debris.
- If you shut off the main water to the house, be aware this affects all fixtures and appliances—plan accordingly.
Common Homeowner Questions
- How long should a toilet tank take to fill? — Generally 1–3 minutes depending on the model and water pressure.
- Can I leave a slow-refilling toilet while I wait for a plumber? — You can, but it wastes water and may indicate a developing problem; shut the supply off if it becomes a leak or nuisance.
- Will replacing the fill valve fix most slow-fill problems? — Yes, in many cases a new fill valve restores normal refill speed if the inlet and supply are fine.