Quick Answer:

If your toilet refill time gets longer week by week, that almost always means something in the water path is slowly restricting flow. Start by checking the shut-off valve, supply line and the fill valve inlet screen for scale or debris. Cleaning those parts often restores normal speed; if it doesn’t, consider replacing the fill valve or calling a plumber.

Why This Happens

Gradual worsening usually points to progressive restriction rather than a sudden failure. Common causes are mineral scale from hard water, small debris trapped in the inlet screen, corrosion inside the supply line, or a partially closed shut-off valve. Over weeks the buildup grows and the refill time lengthens.

Inspect inlet screen and supply line for scale buildup; gradual worsening often points to progressive restriction. You may also see slower flow elsewhere in the house if the supply line or shut-off is the problem. If you want more background on similar symptoms, see Toilet refills slowly and Tank takes forever to fill for related situations and fixes.

Step-by-Step What to Do

Step 1: Establish a baseline

• Time the refill after a flush (from the end of the flush to when the tank is full). Note the time and check again in a day to confirm the trend.
• Check if other fixtures have reduced flow; that helps isolate the problem to the toilet or the house supply.

Step 2: Check the shut-off valve

• Make sure the shut-off behind the toilet is fully open. Turn it gently clockwise until it stops, then counterclockwise to open fully.
• If it’s stiff or leaks, that valve could be restricting flow and may need replacement.

Step 3: Inspect the flexible supply line

• Look for kinks, visible corrosion, or swelling. A damaged braided or rubber line can limit flow.
• If you have a spare supply hose, swap it briefly to see whether refill speed improves.

Step 4: Turn off water and check the fill valve inlet screen

• Shut off the toilet’s supply and flush to empty the tank.
• Disconnect the supply line at the bottom of the tank. Most fill valves have a small metal or plastic inlet screen where the supply connects—remove and inspect it.
• Clean scale and debris with a soft brush and soak in white vinegar for 15–30 minutes if needed. Rinse and reinstall, then test.

Step 5: Test and decide next steps

• If cleaning the screen and ensuring the supply and shut-off are clear fixes the speed, monitor weekly until you’re confident the trend has stopped.
• If flow improves only a little or not at all, replace the fill valve and/or supply line. Fill valves are inexpensive and straightforward to replace for a homeowner comfortable with basic plumbing.

What Not to Do

• Don’t ignore gradual slowdown—it often indicates buildup; if cleaning doesn’t help, a plumber is appropriate.
• Don’t pour strong acids or undiluted chemicals into the tank to remove scale—these can damage seals and the tank finish.
• Don’t force fittings or overtighten connections; use the right tools and a careful touch to avoid cracks or stripped threads.

When to Call a Professional

• Cleaning the inlet screen and replacing the supply line or fill valve doesn’t restore normal refill speed.
• You find corrosion, a leaking shut-off, or a damaged tank fitting that you’re not comfortable repairing.
• The slowdown is housewide (multiple fixtures affected) or you suspect a hidden obstruction in the building supply.

Safety Notes

• Shut off the water at the toilet and/or main before disconnecting fittings. Keep a bucket and towels handy for spills.
• Wear gloves and eye protection when working under the tank or handling cleaning solutions like vinegar.
• If you smell gas, suspect electrical hazards, or discover major corrosion, stop and call a professional instead of attempting repairs yourself.

Common Homeowner Questions

• Q: Can I fix this myself?
  A: Often yes—cleaning the inlet screen and replacing the supply line or fill valve solves most gradual slowdowns.
• Q: Is hard water the likely cause?
  A: Yes, mineral scale from hard water is a common cause of progressive restriction.
• Q: How long before parts should be replaced?
  A: If cleaning doesn’t restore flow in one or two attempts, plan to replace the fill valve or supply line within days to weeks.

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