Quick Answer:
If faucet flow feels different right after a disposal install, don’t panic. Most often the problem is a clogged aerator or a partially closed angle stop you bumped while working. Start by checking whether the low pressure is only at that faucet, then remove and rinse the aerator and confirm the angle stops are fully open. If several fixtures are affected, the cause is elsewhere and a pro may be needed.
Why This Happens
Work under the sink stirs up small debris, pipe scale and plumber’s tape bits. Those particles easily lodge in the faucet aerator screen and cut flow without affecting other fixtures. While installing a disposal, it’s also common to nudge the shutoff handles (angle stops) so they aren’t fully open when you finish.
In rare cases, a kinked supply hose, a loose connection, or a fault in the home’s supply can reduce pressure at more than one fixture. For related post-install issues, you may want to check Sink drains worse after disposal install and Leaks after installing new disposal.
Step-by-Step What to Do
1. Confirm where the pressure change is happening
- Turn on the affected faucet and note the flow.
- Open a different sink faucet and a bathroom fixture briefly. If those have normal pressure, the problem is isolated to the kitchen faucet.
- If low pressure appears at multiple fixtures, stop here — the issue is likely with the main supply or a shared valve.
2. Verify the angle stops are fully open
- Look under the sink at the little shutoff handles on the supply lines (angle stops).
- Turn each stop counterclockwise until it stops so it’s fully open. Don’t force beyond that point.
- Retest the faucet flow after opening the stops completely.
3. Remove and rinse the aerator
- Unscrew the aerator at the tip of the faucet by turning it counterclockwise. You may be able to do this by hand; if not, use pliers with a cloth to protect the finish.
- Separate the screen and rinse it under running water to remove debris. If it’s clogged with sediment, soak briefly in vinegar and rinse.
- Reassemble and screw the aerator back in place. Test the faucet.
4. Check supply hose and fittings if flow is still poor at that faucet
- Look for kinks in flexible supply lines and feel for obvious restrictions at connections.
- If you see a visible leak or a loose nut, gently tighten — don’t overtighten. If you’re not comfortable, call a plumber.
5. If multiple fixtures have low pressure
- Check the home’s main shutoff and any pressure-reducing valve if you have one.
- Contact your water supplier to confirm there are no outages or pressure issues in the area.
What Not to Do
- Don’t assume pressure changes are from the disposal itself—often it’s a disturbed aerator or partially closed stop.
- Don’t try to diagnose broad low-pressure problems by only looking under one sink; if pressure issues affect multiple fixtures, a plumber is appropriate.
- Don’t force fittings or overtighten components; that can damage threads or create leaks.
When to Call a Professional
- If low pressure affects more than one fixture and you can’t identify a simple cause.
- If you find a leak, broken valve, or damaged supply line during checks.
- If you’re uncomfortable turning valves or disconnecting fittings — a licensed plumber can quickly locate and fix supply or valve issues.
Safety Notes
- Before working under the sink, turn off the disposal’s power (unplug it or switch off the breaker) to avoid accidental start-up.
- Shut off the angle stops before disconnecting supply lines to limit water flow. Have a towel and small bucket ready to catch drips.
- Use cloth or tape to protect faucet finishes when using tools on aerators or fittings.
Common Homeowner Questions
- Why did the aerator clog just from installing a disposal? Small bits of debris and pipe scale are disturbed when you work under the sink and can wash into the aerator screen.
- How do I know if the angle stop is fully open? Turn it counterclockwise until it stops; if flow improves afterward, it was likely partly closed.
- Should I call my water supplier or a plumber? Call the supplier for neighborhood-wide pressure drops; call a plumber if multiple fixtures are low or if you find leaks or damaged valves.