Short answer: If the rest of the house is fine, the problem is at the fixture. Unscrew and clean the aerator or showerhead, make sure the shutoff valves under the sink are fully open, and if only the hot side is weak, suspect the cartridge or the water heater. Whole-house weakness is a different problem.
Quick diagnosis
| What you notice | Most likely cause | What to check | Call a pro? |
|---|---|---|---|
| Kitchen faucet weak, others fine | Clogged aerator | Unscrew the tip and look for debris | Rarely |
| Weak after plumbing work or a main shutoff | Debris in the aerator or cartridge | Clean the aerator | If cleaning does not help |
| Weak on hot only | Cartridge, hot shutoff valve or water heater sediment | Check the hot shutoff under the sink | Sometimes |
| Shower weak, sinks fine | Clogged showerhead or flow restrictor | Remove and soak the head | Rarely |
| Pull-down faucet weak | Kinked hose or check valve | Look under the sink at the hose | Sometimes |
Clean the aerator
- Close the drain so small parts do not fall in.
- Unscrew the aerator from the faucet tip (wrap it with tape if you use pliers).
- Rinse out sand and mineral flakes; soak in vinegar for scale.
- Reinstall and test.
Check the shutoff valves
The two small valves under the sink should be fully open (turned counterclockwise). After any repair, someone may have left one partly closed.
Showerheads
Mineral scale clogs the nozzles. Remove the head and soak it in vinegar, or rub the rubber nozzles to break scale loose. Low-flow heads are restricted by design; that is normal.
When to call a professional
- Cleaning the aerator and opening valves does not help.
- The faucet cartridge needs replacing and you are not comfortable doing it.
- The problem spreads to other fixtures.
What it usually costs
Cleaning an aerator or showerhead is free. A plumber typically charges $45 to $150 per hour plus a call-out fee (HomeGuide, 2026).
Frequently asked questions
Why is my kitchen sink water pressure low but not the bathroom?
The cause is at the kitchen faucet itself: a clogged aerator, a partly closed shutoff or a kinked pull-down hose.
Why is only the hot water pressure low?
A partly closed hot shutoff valve, a worn faucet cartridge or sediment in the water heater are the usual causes.
Related problems
Sources
This guide is general information, not a substitute for an inspection by a licensed professional. See our disclaimer.