Kitchen Sink Smells Like Grease After Cooking

Kitchen sink problem: kitchen sink smells like grease after cooking

Quick Answer:

Most often the smell comes from grease collecting in the sink strainer, P‑trap, garbage disposal, or the hose that connects the dishwasher. Start with simple checks and targeted diagnostics — run hot water and dish soap, inspect and remove the P‑trap, and isolate connected appliances. If the odor keeps coming back or you see gurgling or backups, call a plumber.

Why This Happens

  • Grease from cooking cools and sticks to metal and plastic inside the sink drain, disposal, and trap. Over time it traps food particles and starts to smell.
  • Garbage disposals and dishwasher connections can hold residue or drain slowly, letting grease sit and go rancid.
  • Blocked or poorly functioning vents (roof vent or air admittance valve) let trap seals fail or allow odors to move through the drain lines instead of up and out.
  • Loose or leaky fittings around the sink tailpiece or basket strainer can let sanitary odors escape under the cabinet.

Step-by-Step What to Do

1. Do a quick isolation test

  • Run cold water for 30 seconds, then run hot water with a squirt of dish soap for 1–2 minutes. Note whether the smell gets stronger when you run the disposal or dishwasher.
  • If the smell only appears when the disposal runs, keep that observation for diagnostics — it points to a disposal or connected line issue. You may see the same pattern as backs up only when disposal runs.

2. Check and clean the sink strainer and basket

  • Remove the strainer and scrape out any trapped food and grease. Wipe components with paper towels, then wash with hot, soapy water.
  • Do this before trying internal drain work — it often fixes the problem.

3. Inspect and clean the P‑trap

  • Place a bucket under the trap, loosen the slip nuts, and remove the trap. Expect greasy water and solids — use gloves and paper towels.
  • Rinse or scrape the inside. If the trap is full of hardened grease, soak it briefly in hot, soapy water and scrub clean before reinstalling.

4. Test connected appliances and lines

  • Run the dishwasher alone and smell under the sink while it drains. Check the dishwasher hose and air gap for clogs.
  • If smell or backups appear only when using the sprayer, note that pattern — it may indicate a separate pressure or hose issue related to the faucet or sprayer. This can relate to situations like loses pressure only when sprayer is used.
  • Disconnect the dishwasher hose at the tailpiece (after turning off power and water if required) and run water to see if the smell goes away. Reconnect only after confirming the cause.

5. Inspect the garbage disposal

  • Turn off power at the switch and, if possible, at the breaker. Check the splash guard and grinding chamber for trapped grease or food.
  • Use tongs or a flashlight and a gloved hand; do not put your hand into the disposal with power on. Run cold water and grind ice with a little rock salt to clean blades and dislodge residue.

6. Check venting behavior

  • Listen for gurgling when you run sink water or when other fixtures run. Gurgling can mean a blocked vent or a siphoning trap.
  • If venting is suspected (roof vent blocked or failed AAV), this often requires a professional roof or plumbing inspection.

7. Flush with safe cleaners if needed

  • After scrubbing and removing grease manually, flush the drain with very hot water and liquid dish soap to emulsify remaining grease.
  • Use enzyme-based drain products if you want a chemical option — they work slowly to digest organic matter and are gentler than caustic cleaners.

What Not to Do

  • Avoid forcing fittings or over-tightening slip nuts — you can strip threads or crack plastic parts.
  • Do not use caustic drain chemicals (lye-based or strong acids) to clear grease — they can damage pipes, seals, and finishes and create hazardous fumes.
  • Don’t ignore early warning signs like recurring odors, slow drains, or gurgling. Small problems get worse and more expensive to fix.
  • Don’t pour cooking grease down the drain; let it cool and dispose of it in the trash in a sealed container.

When to Call a Professional

  • The smell returns after you clean the strainer and P‑trap, or keeps coming from under the cabinet.
  • You notice persistent backups, sewer‑type odors, or strong gurgling that suggests vent or mainline issues.
  • You’re not comfortable disconnecting the trap, working on the disposal, or if the dishwasher or venting needs inspection at the roof or in confined spaces.
  • If you find leaks, cracked pipes, or repeatedly failing fittings — a plumber can diagnose venting, replace parts, and clear deeper blockages safely.

Safety Notes

  • Always disconnect power before working on a garbage disposal. Turn off the breaker if you’re unsure.
  • Use gloves and eye protection when removing greasy parts or working under the sink.
  • Keep hot water care in mind — scalding risk when running very hot flushes. Handle hot containers carefully.
  • If you use enzyme cleaners, follow label instructions and keep them away from children and pets.

Common Homeowner Questions

  • Can I flush grease down the drain if I run very hot water?
    No — hot water only moves grease farther down where it will cool and stick later. Wipe grease into the trash first.
  • Will enzyme drain cleaners remove grease?
    They can help over time for organic buildup but are not instant. Combine with manual cleaning for best results.
  • Is a grease smell the same as a sewer smell?
    Not usually. Grease smells rancid and localized. A sewer smell is stronger, sulfurous, and may mean a broken seal or sewer issue — call a plumber.

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