A toilet tank that will not fill may have a closed shutoff valve, stuck float, blocked fill valve, or low supply pressure. Start with visible tank parts and the external shutoff; do not force plastic connections or disassemble the valve with the water on.
Confirm the shutoff valve is open
The valve beside the toilet may have been closed during service. Turn it only as designed and stop if it is seized or starts leaking; forcing an old valve can damage it.
See whether the float is stuck
With the lid carefully removed, see whether the float is caught against the tank wall, chain, or another part. Free simple interference without bending mechanisms or randomly changing settings.
A fill valve can clog with sediment
If other fixtures have normal pressure but the tank receives little water, the inlet or fill valve may be restricted. Shut off water before following the manufacturer’s cleaning or replacement procedure.
Low flow at several fixtures points to the supply
If other faucets have also lost pressure, do not focus only on the toilet. Check the main supply, recent work, or utility conditions and respond according to the scope of the problem.
Sources
- U.S. Environmental Protection Agency (EPA) — WaterSense Home Maintenance — Household water maintenance, leaks, fixtures, and efficiency.