Kitchen sink slow but bathroom fine

Kitchen sink draining slowly while bathroom drains normally

Quick Answer:

If only the kitchen sink is slow and other fixtures run normally, the problem is usually local to the kitchen line — things like food, grease, a clogged P‑trap, or a partial garbage disposal jam. Start by confirming other sinks drain normally, then try the simple checks below before calling a plumber.

Why This Happens

A slow kitchen sink with good flow elsewhere almost always points to a blockage or restriction in the kitchen drain path rather than a main sewer problem. Common causes include:

  • Food scraps and grease buildup inside the pipe or P‑trap.
  • Partial jams in a garbage disposal or debris caught at the disposal outlet.
  • A kinked or crushed dishwasher drain hose if your dishwasher shares the line.
  • Vent issues or slow buildup over time — this is different from a full mainline clog that would affect multiple drains.

Two patterns homeowners notice are a Slow drain after long vacation when grease hardens, and a Slow drain worsens over time with gradual buildup from regular use.

Step-by-Step What to Do

Step 1 — Confirm other sinks and fixtures

  • Run water in the bathroom sink, tub, and other kitchen faucets. If they drain normally, the issue is local to the kitchen line or disposal.

Step 2 — Check the garbage disposal

  • Turn off power to the disposal at the wall or breaker before inspecting.
  • Look for visible jams and remove any large debris with pliers. Do not put your hand into the disposal while it might be powered.
  • After clearing, restore power and run cold water while turning the disposal on to test flow.

Step 3 — Use a plunger

  • Block the sink’s overflow or the other basin if you have a double sink, then plunge the slow basin with a cup plunger to try to dislodge the clog.
  • Keep water level high enough to cover the plunger cup for a good seal.

Step 4 — Remove and inspect the P‑trap

  • Place a bucket underneath, loosen the slip nuts, and remove the P‑trap. Clean out grease and debris by hand or with a brush.
  • Reassemble carefully and run water to check if flow returns to normal.

Step 5 — Try a hand auger or sink snake

  • If the trap is clear but the sink is still slow, feed a small hand auger into the drain to reach and break up clogs in the trap arm or immediate downstream pipe.
  • Do not use power augers intended for toilets on kitchen pipes — they can damage thinner drain lines.

Step 6 — Test and watch for recurrence

  • Run hot water for several minutes and observe how quickly the sink clears. If the sink clears but slows again soon, you may have a recurring grease problem.
  • Keep an eye on dishwasher drainage too if it ties into the same line.

What Not to Do

  • Do not ignore isolated kitchen drain issues — small clogs often get worse and can lead to backups or odor problems.
  • Do not reach into a disposal while it could be powered on.
  • Do not pour strong chemical drain cleaners into a disposal or down a recently disassembled trap; they can be dangerous and damage pipes or finishes.
  • Do not force a pipe or fitting if it’s stuck; use proper tools or call for help to avoid breaking the connection.

When to Call a Professional

  • The clog doesn’t clear after removing the trap and using a hand auger.
  • Multiple fixtures start to slow or you see sewage backing up—this suggests a mainline or sewer issue.
  • You find a leak you can’t safely repair, or the disposal is damaged and needs replacement.
  • The problem recurs quickly despite cleaning — this may need professional diagnosis or a deeper run snake to reach farther blockages.

Safety Notes

  • Always cut power to a garbage disposal before working on it. Test the switch to be sure it’s off.
  • Wear gloves and eye protection when removing debris; pipes can hold sharp objects or hot water.
  • Avoid mixing chemical drain cleaners with other solutions or using them after mechanical work — residues can cause burns or release harmful fumes.
  • If you smell sewer gas or see signs of a larger backup, leave the area and call a pro promptly.

Common Homeowner Questions

  • Why does only the kitchen sink drain slowly? — Most often a local clog from food or grease, or a disposal/trap issue rather than a main sewer problem.
  • Can I fix this myself? — Often yes: clearing the disposal, plunging, or cleaning the P‑trap solves common slow drains.
  • Will pouring boiling water help? — It can soften grease and help flush small buildups, but use caution with PVC pipes (don’t pour scalding water repeatedly) and don’t rely on it for stubborn clogs.

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