A whistling faucet usually has a restriction that speeds up water: a partly blocked aerator, worn cartridge, partially closed shutoff, or high pressure. Timing and whether the sound occurs on hot, cold, or both sides help locate the cause without unnecessary disassembly.
Remove and clean the aerator first
Turn the faucet off, remove the aerator if designed to be serviced, and clean sediment and scale. Run a brief test without it; if the whistle disappears, the restriction has been located.
Hot-only or cold-only noise points to that side
If the sound changes with handle position, wear or restriction may be in the cartridge, valve, or supply line on that side. Shut off water before any disassembly following the fixture instructions.
A partly closed shutoff can create noise
Check that the valves under the sink are in their normal operating position without forcing them. An old valve that is seized or leaks when moved needs repair rather than more force.
Whistling at several faucets can indicate high pressure
If the sound appears at different fixtures and flow is unusually forceful, measure pressure with suitable equipment or arrange inspection. Do not randomly adjust the main pressure regulator because it affects the whole plumbing system.
Sources
- U.S. Environmental Protection Agency (EPA) — WaterSense Home Maintenance — Household water maintenance, leaks, fixtures, and efficiency.