Make three comparisons before disassembly
This faucet versus nearby fixtures
Run a nearby sink or tub. If it is weak too, look beyond this faucet toward the branch, pressure regulator, water treatment equipment, service line, or utility.
Hot versus cold
Run the affected faucet fully cold, then fully hot. One weak side points toward its shutoff, connector, or cartridge inlet. Both sides share the aerator, spray head, diverter, and mixed outlet.
Spout versus spray
On a pull-down, pull-out, or side-spray faucet, compare its outlets. One weak mode can point toward a spray head, hose, diverter, or mode-specific restriction.
Follow the water from the shutoff to the outlet
| Flow point | What can restrict it |
|---|---|
| Fixture shutoff | A partly closed stem, internal damage, or debris in the valve. |
| Supply connector | A kink, internal collapse, trapped debris, or poor routing. |
| Cartridge or faucet body | Debris, scale, damaged parts, or a control that no longer opens fully. |
| Diverter, hose, and spray path | A pinched hose, internal restriction, or switching problem. |
| Aerator or spray head | Scale, sediment, a damaged screen, or parts assembled in the wrong order. |
If both sides are weak, check the outlet first
- Close the drain so small parts cannot fall in, and protect the faucet finish.
- Use the manufacturer's key or instructions for a recessed or hidden aerator. Do not grip a finished part with bare pliers.
- Record the order of screens, washers, and flow components before removing them.
- Rinse loose debris and use only a scale cleaner allowed for those materials and the faucet finish. EPA recommends removing buildup that restricts flow. [3]
- Reassemble every required part in its original order, then test both flow and leaks.
When the outlet is not the problem
If cleaning the outlet does not improve both hot and cold flow, the next check depends on the model. The restriction may be in the spray head, hose, diverter, cartridge, or faucet body. Kohler's troubleshooting steps vary by faucet and call for model-specific replacement parts. [1]
A sudden change after utility work, water-heater service, filter maintenance, or a shutoff event can move debris into the fixture. Record what happened and whether hot or cold is affected. Do not flush an open valve body unless the water can be controlled and the manufacturer gives a safe procedure.
Details that make diagnosis easier
- The faucet brand and model, its approximate age if known, and photographs of the handle and outlet.
- Whether hot, cold, both temperatures, the spout, or a spray mode is affected.
- Whether the change was sudden or gradual and whether utility, plumbing, filter, or water-heater work came first.
- Whether removing or cleaning the aerator changed the flow and what debris was present.
- The condition of the shutoff valves and supply connectors, including any corrosion or leakage.