A toilet tank should refill completely in 1–2 minutes after flushing. If it's taking 3+ minutes, you're almost always dealing with a clogged fill valve screen, low water pressure at the shutoff valve, or a worn fill valve.
Likelihood: Very common — check this first
The shutoff valve behind the toilet (the oval handle on the wall) controls water flow to the toilet. If it's not fully open, flow is restricted.
Fix: Turn the oval valve counterclockwise until it stops. If a ball valve style, make sure the handle is parallel to the pipe.
Likelihood: Common
Most fill valves have a small filter screen at the bottom that traps debris. This screen can clog with sediment, especially in homes with older pipes or after plumbing work.
Fix: Clean or replace the fill valve screen (cap-and-screen on Fluidmaster valves twist off).
Likelihood: Common in older toilets
Over years of use, the fill valve's internal parts wear and restrict flow.
Fix: Replace the fill valve ($10–20). Takes about 20 minutes.
Likelihood: Less common
If multiple fixtures in your home run slow, the issue may be house-wide low pressure, not the toilet itself.
Fix: Test pressure at an outdoor spigot. Normal is 40–80 psi. Below 40 may indicate a pressure regulator problem.
Locate the oval handle behind and below the toilet. Turn it fully counterclockwise. You'll know it was partially closed if the fill speed improves immediately.
Turn off the shutoff valve. Flush to relieve pressure. On Fluidmaster-style valves, hold the top of the fill valve and twist the cap counterclockwise 1/8 turn to remove. Pull out the seal and screen. Rinse debris under running water, reinstall, and test.
Turn off water, flush tank empty, disconnect supply line. Reach under tank and unscrew the locknut (counterclockwise) using adjustable pliers. Pull old valve out through the tank. Insert new fill valve, adjust height to 1 inch below overflow tube, tighten locknut. Reconnect supply line and turn water on.
Plumbing work often dislodges debris in pipes that then settles in the toilet's fill valve screen. Turn off the water and clean the fill valve screen — this almost always resolves post-plumbing-work slow fill.
A high-pitched squeal during fill is a sign of a deteriorating fill valve diaphragm or seal. Cleaning sometimes helps, but replacing the fill valve ($15) is the permanent fix.
Call a plumber if you find the shutoff valve is frozen/corroded and won't fully open, or if house water pressure is below 40 psi (pressure regulator adjustment required).
ChatDIY can adapt this diagnosis to your exact fixture, tools, photos, and skill level.