Symptoms
- Drip or sputter coincides with the washing machine, dishwasher, or toilet running elsewhere
- Faucet is fine when it's the only fixture in use
- Effect is more noticeable with a worn or older cartridge
- House has relatively low overall water pressure
Likely causes
- CommonCartridge marginally worn and sensitive to pressure changesA cartridge nearing the end of its life may seal less reliably when pressure fluctuates.
- PossibleOverall low household water pressureMultiple fixtures drawing water at once can cause momentary pressure drops that affect a marginal seal.
- PossiblePartially closed shutoff valve reducing available pressure marginLeaves less pressure buffer when demand spikes elsewhere.
- Less commonUndersized supply piping to that fixtureMore common in older homes with narrow branch lines.
What to do
- Note exactly which other fixture triggers the drip to help narrow down shared plumbing lines.
- Confirm the shutoff valves under the sink for the affected faucet are fully open.
- If the faucet's cartridge is old, treat this as an early sign and consider replacing it proactively.
- Check overall household water pressure with a gauge on an outdoor spigot if available; normal is roughly 40–60 psi.
- If pressure is on the low side, a plumber can evaluate whether a pressure booster or larger supply line would help.
- If it's a minor, occasional drip and pressure is otherwise normal, monitor it rather than treating it as urgent.
Tools and parts
- Pressure gauge (optional)
Faucet cartridgeSearch: “faucet cartridge replacement kit”
When to call a pro
Call a plumber if low household pressure seems to be the underlying cause, since that may need a broader fix than the faucet itself.
Safety
Generally low risk
Generally low risk for a careful person. Stop if anything looks different from what this guide describes.